target/linux/generic/pending-5.10/402-mtd-spi-nor-write-support-for-minor-aligned-partitions.patch

   1 From patchwork Tue Jun  8 04:07:19 2021
   2 Content-Type: text/plain; charset="utf-8"
   3 MIME-Version: 1.0
   4 Content-Transfer-Encoding: 7bit
   5 X-Patchwork-Submitter: John Thomson <git@johnthomson.fastmail.com.au>
   6 X-Patchwork-Id: 1489105
   7 X-Patchwork-Delegate: tudor.ambarus@gmail.com
   8 Return-Path:
   9  <linux-mtd-bounces+incoming=patchwork.ozlabs.org@lists.infradead.org>
  10 X-Original-To: incoming@patchwork.ozlabs.org
  11 Delivered-To: patchwork-incoming@bilbo.ozlabs.org
  12 Authentication-Results: ozlabs.org;
  13  spf=none (no SPF record) smtp.mailfrom=lists.infradead.org
  14  (client-ip=2607:7c80:54:e::133; helo=bombadil.infradead.org;
  15  envelope-from=linux-mtd-bounces+incoming=patchwork.ozlabs.org@lists.infradead.org;
  16  receiver=<UNKNOWN>)
  17 Authentication-Results: ozlabs.org;
  18         dkim=pass (2048-bit key;
  19  secure) header.d=lists.infradead.org header.i=@lists.infradead.org
  20  header.a=rsa-sha256 header.s=bombadil.20210309 header.b=EMabhVoR;
  21         dkim=fail reason="signature verification failed" (2048-bit key;
  22  unprotected) header.d=fastmail.com.au header.i=@fastmail.com.au
  23  header.a=rsa-sha256 header.s=fm3 header.b=dLzuZ6dB;
  24         dkim=fail reason="signature verification failed" (2048-bit key;
  25  unprotected) header.d=messagingengine.com header.i=@messagingengine.com
  26  header.a=rsa-sha256 header.s=fm3 header.b=nSRGsW+C;
  27         dkim-atps=neutral
  28 Received: from bombadil.infradead.org (bombadil.infradead.org
  29  [IPv6:2607:7c80:54:e::133])
  30         (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)
  31          key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest
  32  SHA256)
  33         (No client certificate requested)
  34         by ozlabs.org (Postfix) with ESMTPS id 4FzcFN1j1nz9sW8
  35         for <incoming@patchwork.ozlabs.org>; Tue,  8 Jun 2021 14:09:28 +1000 (AEST)
  36 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed;
  37         d=lists.infradead.org; s=bombadil.20210309; h=Sender:
  38         Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post:
  39         List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-Id:Date:Subject:Cc
  40         :To:From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From:
  41         Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References:
  42         List-Owner; bh=6mUWQd71FwsINycGYY1qOhKz+ecWJVNtwDkTebG3XkA=; b=EMabhVoRE3ad89
  43         o3L2AgyKrs+blSofUC3hoSsQe7gi3m4si8S9HW8Z+8SsS5TufUsvGwDl80qSYGlQOytQF+1yRUWvE
  44         6FJ/+bqv+TwjqZFibgJ6+9OVsQN9dZ/no1R0bBXIpmrf8ORUmv58QK4ZQquaFKbyXKpFeWOC2MSv4
  45         H2MAhyhTU8a3gtooH6G8+KvsJEfVgh6C+aDbwxyh2UY3chHKuw1kvL6AktbfUE2xl4zxi3x3kc70B
  46         Wi3LiJBFokxVdgnROXxTU5tI0XboWYkQV64gLuQNV4XKClcuhVpzloDK8Iok6NTd7b32a7TdEFlCS
  47         lGKsEKmxtUlW2FpfoduA==;
  48 Received: from localhost ([::1] helo=bombadil.infradead.org)
  49         by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux))
  50         id 1lqT1r-006OAW-DX; Tue, 08 Jun 2021 04:07:51 +0000
  51 Received: from new1-smtp.messagingengine.com ([66.111.4.221])
  52  by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux))
  53  id 1lqT1l-006O9b-Fq
  54  for linux-mtd@lists.infradead.org; Tue, 08 Jun 2021 04:07:50 +0000
  55 Received: from compute2.internal (compute2.nyi.internal [10.202.2.42])
  56  by mailnew.nyi.internal (Postfix) with ESMTP id 4456B580622;
  57  Tue,  8 Jun 2021 00:07:42 -0400 (EDT)
  58 Received: from mailfrontend2 ([10.202.2.163])
  59  by compute2.internal (MEProxy); Tue, 08 Jun 2021 00:07:42 -0400
  60 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fastmail.com.au;
  61  h=from:to:cc:subject:date:message-id:mime-version
  62  :content-transfer-encoding; s=fm3; bh=ZXRH+YluM1mHCS1EWUiCY/Sg8O
  63  LccfHe1oW5iAay6y8=; b=dLzuZ6dBYf7ZA8tWLOBFZYLi7ERsGe/4vnMXG+ovvb
  64  dNBO0+SaFGwoqYSFrfq/TeyHfKyvxrA7+LCdopIuT4abpLHxtRwtRiafQcDYCPat
  65  qJIqOZO+wCZC5S9Jc1OP7+t1FviGpgevqIMotci37P+RWc5u3AweMzFljZk90E8C
  66  uorV6rXagD+OssJQzllRnAIK88+rOAC9ZyXv2gWxy4d1HSCwSWgzx2vnV9CNp918
  67  YC/3tiHas9krbrPIaAsdBROr7Bvoe/ShRRzruKRuvZVgg5NN90vX+/5ZjI8u04GM
  68  p2bWCbC62CP6wlcgDaz+c/Sgr5ITd2GPENJsHfqmLRBA==
  69 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=
  70  messagingengine.com; h=cc:content-transfer-encoding:date:from
  71  :message-id:mime-version:subject:to:x-me-proxy:x-me-proxy
  72  :x-me-sender:x-me-sender:x-sasl-enc; s=fm3; bh=ZXRH+YluM1mHCS1EW
  73  UiCY/Sg8OLccfHe1oW5iAay6y8=; b=nSRGsW+CQ2Zx1RVpIUu8W/VD/k5P+32BW
  74  5k2ltd+UhI3dfldBPzHrYiOP/IJqGkNW+V+rHASacW/vFygnaZoxNjRYKnOsu+26
  75  wb2yK3jpl6lsNTg3N1Z4XJrYY2lf9H29DMFbhC67l0PTc050rcZk4XsKTLAlv14Q
  76  VA4WREYSaX/4IN4O+ES4TMq0a/3gKZh6nvbbJXbsXfK0WlSHTGZtZmW3fyrqvbXa
  77  t+R7L8vvqWvwls0pV+Sn8LeQqb7+A69w0UOnuznjkcA3sCc2YehcHbxcUEnMH+9N
  78  bxOjmIDeg9/4X/829tUWUJiLhE5SFmQZ1P6oFtmbWoLrDz0ZJIVBw==
  79 X-ME-Sender: <xms:C-2-YD2uka4HsA6gcdsV2Ia7vebY4Yjp9E8q7KBMb54jnAzGL7-67Q>
  80  <xme:C-2-YCEaxASy5VlcrvNO_jLFpMDGkFCRsuVNuZGEQsiRZygk8jPHWq7unPjeT6uYS
  81  2pUP6PrTQ2rggjEIg>
  82 X-ME-Received:
  83  <xmr:C-2-YD4exeK49N_YZWWf2BWDhVyCbCY3wwvjTyDOFxeugx7Jg08pzMUToo9oJjrBpcVTaA3kbfk>
  84 X-ME-Proxy-Cause:
  85  gggruggvucftvghtrhhoucdtuddrgeduledrfedtkedgjeduucetufdoteggodetrfdotf
  86  fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen
  87  uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne
  88  cujfgurhephffvufffkffoggfgsedtkeertdertddtnecuhfhrohhmpeflohhhnhcuvfhh
  89  ohhmshhonhcuoehgihhtsehjohhhnhhthhhomhhsohhnrdhfrghsthhmrghilhdrtghomh
  90  drrghuqeenucggtffrrghtthgvrhhnpefffeeihfdukedtuedufeetieeuudfhhefhkefh
  91  tefgtdeuffekffelleetveduieenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmh
  92  epmhgrihhlfhhrohhmpehgihhtsehjohhhnhhthhhomhhsohhnrdhfrghsthhmrghilhdr
  93  tghomhdrrghu
  94 X-ME-Proxy: <xmx:C-2-YI0AJZGjcB3wIbI9BoC9X8VNl4i9A7cQnBkvwZ25czWJlkKCLw>
  95  <xmx:C-2-YGGufw99T-O81-FeiSyEruv6_Pr0IHFhspQdxjv5k1VFTZ0lzQ>
  96  <xmx:C-2-YJ8BW7DhSDSCEAPSJWrwh_hHP79qreTZtWh_kOUwSh1c0MMlAg>
  97  <xmx:Du2-YJBeX2Fg9oFZVXGwEJ1ZrZnXHiAqNON8tbpzquYgcm2o_LM48g>
  98 Received: by mail.messagingengine.com (Postfix) with ESMTPA; Tue,
  99  8 Jun 2021 00:07:35 -0400 (EDT)
 100 From: John Thomson <git@johnthomson.fastmail.com.au>
 101 To: Miquel Raynal <miquel.raynal@bootlin.com>,
 102  Richard Weinberger <richard@nod.at>, Vignesh Raghavendra <vigneshr@ti.com>,
 103  Tudor Ambarus <tudor.ambarus@microchip.com>,
 104  Michael Walle <michael@walle.cc>, Pratyush Yadav <p.yadav@ti.com>,
 105  linux-mtd@lists.infradead.org
 106 Cc: linux-kernel@vger.kernel.org,
 107  John Thomson <git@johnthomson.fastmail.com.au>,
 108  kernel test robot <lkp@intel.com>, Dan Carpenter <dan.carpenter@oracle.com>
 109 Subject: [PATCH] mtd: spi-nor: write support for minor aligned partitions
 110 Date: Tue,  8 Jun 2021 14:07:19 +1000
 111 Message-Id: <20210608040719.14431-1-git@johnthomson.fastmail.com.au>
 112 X-Mailer: git-send-email 2.31.1
 113 MIME-Version: 1.0
 114 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3
 115 X-CRM114-CacheID: sfid-20210607_210745_712053_67A7D864
 116 X-CRM114-Status: GOOD (  26.99  )
 117 X-Spam-Score: -0.8 (/)
 118 X-Spam-Report: Spam detection software,
 119  running on the system "bombadil.infradead.org",
 120  has NOT identified this incoming email as spam.  The original
 121  message has been attached to this so you can view it or label
 122  similar future email.  If you have any questions, see
 123  the administrator of that system for details.
 124  Content preview:  Do not prevent writing to mtd partitions where a partition
 125  boundary sits on a minor erasesize boundary. This addresses a FIXME that
 126  has been present since the start of the linux git history: /* Doesn' [...]
 127  Content analysis details:   (-0.8 points, 5.0 required)
 128  pts rule name              description
 129  ---- ----------------------
 130  --------------------------------------------------
 131  -0.7 RCVD_IN_DNSWL_LOW      RBL: Sender listed at https://www.dnswl.org/,
 132  low trust [66.111.4.221 listed in list.dnswl.org]
 133  -0.0 SPF_PASS               SPF: sender matches SPF record
 134  -0.0 SPF_HELO_PASS          SPF: HELO matches SPF record
 135  0.0 RCVD_IN_MSPIKE_H3      RBL: Good reputation (+3)
 136  [66.111.4.221 listed in wl.mailspike.net]
 137  -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature
 138  0.1 DKIM_SIGNED            Message has a DKIM or DK signature,
 139  not necessarily
 140  valid
 141  -0.1 DKIM_VALID_EF          Message has a valid DKIM or DK signature from
 142  envelope-from domain
 143  0.0 RCVD_IN_MSPIKE_WL      Mailspike good senders
 144 X-BeenThere: linux-mtd@lists.infradead.org
 145 X-Mailman-Version: 2.1.34
 146 Precedence: list
 147 List-Id: Linux MTD discussion mailing list <linux-mtd.lists.infradead.org>
 148 List-Unsubscribe: <http://lists.infradead.org/mailman/options/linux-mtd>,
 149  <mailto:linux-mtd-request@lists.infradead.org?subject=unsubscribe>
 150 List-Archive: <http://lists.infradead.org/pipermail/linux-mtd/>
 151 List-Post: <mailto:linux-mtd@lists.infradead.org>
 152 List-Help: <mailto:linux-mtd-request@lists.infradead.org?subject=help>
 153 List-Subscribe: <http://lists.infradead.org/mailman/listinfo/linux-mtd>,
 154  <mailto:linux-mtd-request@lists.infradead.org?subject=subscribe>
 155 Sender: "linux-mtd" <linux-mtd-bounces@lists.infradead.org>
 156 Errors-To: linux-mtd-bounces+incoming=patchwork.ozlabs.org@lists.infradead.org
 157
 158 Do not prevent writing to mtd partitions where a partition boundary sits
 159 on a minor erasesize boundary.
 160 This addresses a FIXME that has been present since the start of the
 161 linux git history:
 162 /* Doesn't start on a boundary of major erase size */
 163 /* FIXME: Let it be writable if it is on a boundary of
 164  * _minor_ erase size though */
 165
 166 Allow a uniform erase region spi-nor device to be configured
 167 to use the non-uniform erase regions code path for an erase with:
 168 CONFIG_MTD_SPI_NOR_USE_VARIABLE_ERASE=y
 169
 170 On supporting hardware (SECT_4K: majority of current SPI-NOR device)
 171 provide the facility for an erase to use the least number
 172 of SPI-NOR operations, as well as access to 4K erase without
 173 requiring CONFIG_MTD_SPI_NOR_USE_4K_SECTORS
 174
 175 Introduce erasesize_minor to the mtd struct,
 176 the smallest erasesize supported by the device
 177
 178 On existing devices, this is useful where write support is wanted
 179 for data on a 4K partition, such as some u-boot-env partitions,
 180 or RouterBoot soft_config, while still netting the performance
 181 benefits of using 64K sectors
 182
 183 Performance:
 184 time mtd erase firmware
 185 OpenWrt 5.10 ramips MT7621 w25q128jv 0xfc0000 partition length
 186
 187 Without this patch
 188 MTD_SPI_NOR_USE_4K_SECTORS=y    |n
 189 real    2m 11.66s               |0m 50.86s
 190 user    0m 0.00s                |0m 0.00s
 191 sys     1m 56.20s               |0m 50.80s
 192
 193 With this patch
 194 MTD_SPI_NOR_USE_VARIABLE_ERASE=n|y              |4K_SECTORS=y
 195 real    0m 51.68s               |0m 50.85s      |2m 12.89s
 196 user    0m 0.00s                |0m 0.00s       |0m 0.01s
 197 sys     0m 46.94s               |0m 50.38s      |2m 12.46s
 198
 199 Signed-off-by: John Thomson <git@johnthomson.fastmail.com.au>
 200 ---
 201 Have not tested on variable erase regions device.
 202
 203 checkpatch does not like the printk(KERN_WARNING
 204 these should be changed separately beforehand?
 205
 206 Changes RFC -> v1:
 207 Fix uninitialized variable smatch warning
 208 Reported-by: kernel test robot <lkp@intel.com>
 209 Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
 210 ---
 211  drivers/mtd/mtdpart.c       | 52 ++++++++++++++++++++++++++++---------
 212  drivers/mtd/spi-nor/Kconfig | 10 +++++++
 213  drivers/mtd/spi-nor/core.c  | 10 +++++--
 214  include/linux/mtd/mtd.h     |  2 ++
 215  4 files changed, 60 insertions(+), 14 deletions(-)
 216
 217 --- a/drivers/mtd/mtdpart.c
 218 +++ b/drivers/mtd/mtdpart.c
 219 @@ -40,10 +40,11 @@ static struct mtd_info *allocate_partiti
 220         struct mtd_info *master = mtd_get_master(parent);
 221         int wr_alignment = (parent->flags & MTD_NO_ERASE) ?
 222                            master->writesize : master->erasesize;
 223 +       int wr_alignment_minor = 0;
 224         u64 parent_size = mtd_is_partition(parent) ?
 225                           parent->part.size : parent->size;
 226         struct mtd_info *child;
 227 -       u32 remainder;
 228 +       u32 remainder, remainder_minor;
 229         char *name;
 230         u64 tmp;
 231
 232 @@ -145,6 +146,7 @@ static struct mtd_info *allocate_partiti
 233                 int i, max = parent->numeraseregions;
 234                 u64 end = child->part.offset + child->part.size;
 235                 struct mtd_erase_region_info *regions = parent->eraseregions;
 236 +               uint32_t erasesize_minor = child->erasesize;
 237
 238                 /* Find the first erase regions which is part of this
 239                  * partition. */
 240 @@ -155,15 +157,24 @@ static struct mtd_info *allocate_partiti
 241                 if (i > 0)
 242                         i--;
 243
 244 -               /* Pick biggest erasesize */
 245                 for (; i < max && regions[i].offset < end; i++) {
 246 +                       /* Pick biggest erasesize */
 247                         if (child->erasesize < regions[i].erasesize)
 248                                 child->erasesize = regions[i].erasesize;
 249 +                       /* Pick smallest non-zero erasesize */
 250 +                       if ((erasesize_minor > regions[i].erasesize) && (regions[i].erasesize > 0))
 251 +                               erasesize_minor = regions[i].erasesize;
 252                 }
 253 +
 254 +               if (erasesize_minor < child->erasesize)
 255 +                       child->erasesize_minor = erasesize_minor;
 256 +
 257                 BUG_ON(child->erasesize == 0);
 258         } else {
 259                 /* Single erase size */
 260                 child->erasesize = master->erasesize;
 261 +               if (master->erasesize_minor)
 262 +                       child->erasesize_minor = master->erasesize_minor;
 263         }
 264
 265         /*
 266 @@ -171,26 +182,43 @@ static struct mtd_info *allocate_partiti
 267          * exposes several regions with different erasesize. Adjust
 268          * wr_alignment accordingly.
 269          */
 270 -       if (!(child->flags & MTD_NO_ERASE))
 271 +       if (!(child->flags & MTD_NO_ERASE)) {
 272                 wr_alignment = child->erasesize;
 273 +               if (IS_ENABLED(CONFIG_MTD_SPI_NOR_USE_VARIABLE_ERASE) && child->erasesize_minor)
 274 +                       wr_alignment_minor = child->erasesize_minor;
 275 +       }
 276
 277         tmp = mtd_get_master_ofs(child, 0);
 278         remainder = do_div(tmp, wr_alignment);
 279         if ((child->flags & MTD_WRITEABLE) && remainder) {
 280 -               /* Doesn't start on a boundary of major erase size */
 281 -               /* FIXME: Let it be writable if it is on a boundary of
 282 -                * _minor_ erase size though */
 283 -               child->flags &= ~MTD_WRITEABLE;
 284 -               printk(KERN_WARNING"mtd: partition \"%s\" doesn't start on an erase/write block boundary -- force read-only\n",
 285 -                       part->name);
 286 +               if (wr_alignment_minor) {
 287 +                       tmp = mtd_get_master_ofs(child, 0);
 288 +                       remainder_minor = do_div(tmp, wr_alignment_minor);
 289 +                       if (remainder_minor == 0)
 290 +                               child->erasesize = child->erasesize_minor;
 291 +               }
 292 +
 293 +               if ((!wr_alignment_minor) || (wr_alignment_minor && remainder_minor != 0)) {
 294 +                       child->flags &= ~MTD_WRITEABLE;
 295 +                       printk(KERN_WARNING"mtd: partition \"%s\" doesn't start on an erase/write block boundary -- force read-only\n",
 296 +                               part->name);
 297 +               }
 298         }
 299
 300         tmp = mtd_get_master_ofs(child, 0) + child->part.size;
 301         remainder = do_div(tmp, wr_alignment);
 302         if ((child->flags & MTD_WRITEABLE) && remainder) {
 303 -               child->flags &= ~MTD_WRITEABLE;
 304 -               printk(KERN_WARNING"mtd: partition \"%s\" doesn't end on an erase/write block -- force read-only\n",
 305 -                       part->name);
 306 +               if (wr_alignment_minor) {
 307 +                       tmp = mtd_get_master_ofs(child, 0) + child->part.size;
 308 +                       remainder_minor = do_div(tmp, wr_alignment_minor);
 309 +                       if (remainder_minor == 0)
 310 +                               child->erasesize = child->erasesize_minor;
 311 +               }
 312 +               if ((!wr_alignment_minor) || (wr_alignment_minor && remainder_minor != 0)) {
 313 +                       child->flags &= ~MTD_WRITEABLE;
 314 +                       printk(KERN_WARNING"mtd: partition \"%s\" doesn't end on an erase/write block -- force read-only\n",
 315 +                               part->name);
 316 +               }
 317         }
 318
 319         child->size = child->part.size;
 320 --- a/drivers/mtd/spi-nor/Kconfig
 321 +++ b/drivers/mtd/spi-nor/Kconfig
 322 @@ -10,6 +10,16 @@ menuconfig MTD_SPI_NOR
 323
 324  if MTD_SPI_NOR
 325
 326 +config MTD_SPI_NOR_USE_VARIABLE_ERASE
 327 +       bool "Disable uniform_erase to allow use of all hardware supported erasesizes"
 328 +       depends on !MTD_SPI_NOR_USE_4K_SECTORS
 329 +       default n
 330 +       help
 331 +         Allow mixed use of all hardware supported erasesizes,
 332 +         by forcing spi_nor to use the multiple eraseregions code path.
 333 +         For example: A 68K erase will use one 64K erase, and one 4K erase
 334 +         on supporting hardware.
 335 +
 336  config MTD_SPI_NOR_USE_4K_SECTORS
 337         bool "Use small 4096 B erase sectors"
 338         default y
 339 --- a/drivers/mtd/spi-nor/core.c
 340 +++ b/drivers/mtd/spi-nor/core.c
 341 @@ -1084,6 +1084,8 @@ static u8 spi_nor_convert_3to4_erase(u8
 342
 343  static bool spi_nor_has_uniform_erase(const struct spi_nor *nor)
 344  {
 345 +       if (IS_ENABLED(CONFIG_MTD_SPI_NOR_USE_VARIABLE_ERASE))
 346 +               return false;
 347         return !!nor->params->erase_map.uniform_erase_type;
 348  }
 349
 350 @@ -2569,6 +2571,7 @@ static int spi_nor_select_erase(struct s
 351  {
 352         struct spi_nor_erase_map *map = &nor->params->erase_map;
 353         const struct spi_nor_erase_type *erase = NULL;
 354 +       const struct spi_nor_erase_type *erase_minor = NULL;
 355         struct mtd_info *mtd = &nor->mtd;
 356         u32 wanted_size = nor->info->sector_size;
 357         int i;
 358 @@ -2601,8 +2604,9 @@ static int spi_nor_select_erase(struct s
 359          */
 360         for (i = SNOR_ERASE_TYPE_MAX - 1; i >= 0; i--) {
 361                 if (map->erase_type[i].size) {
 362 -                       erase = &map->erase_type[i];
 363 -                       break;
 364 +                       if (!erase)
 365 +                               erase = &map->erase_type[i];
 366 +                       erase_minor = &map->erase_type[i];
 367                 }
 368         }
 369
 370 @@ -2610,6 +2614,8 @@ static int spi_nor_select_erase(struct s
 371                 return -EINVAL;
 372
 373         mtd->erasesize = erase->size;
 374 +       if (erase_minor && erase_minor->size < erase->size)
 375 +               mtd->erasesize_minor = erase_minor->size;
 376         return 0;
 377  }
 378
 379 --- a/include/linux/mtd/mtd.h
 380 +++ b/include/linux/mtd/mtd.h
 381 @@ -242,6 +242,8 @@ struct mtd_info {
 382          * information below if they desire
 383          */
 384         uint32_t erasesize;
 385 +       /* "Minor" (smallest) erase size supported by the whole device */
 386 +       uint32_t erasesize_minor;
 387         /* Minimal writable flash unit size. In case of NOR flash it is 1 (even
 388          * though individual bits can be cleared), in case of NAND flash it is
 389          * one NAND page (or half, or one-fourths of it), in case of ECC-ed NOR