target/linux/brcm2708/patches-4.4/0185-bcm2835-sdhost-Workaround-for-slow-sectors.patch

   1 From 95ca033cb9ac492b060c0cc44093180871e8d63b Mon Sep 17 00:00:00 2001
   2 From: Phil Elwell <phil@raspberrypi.org>
   3 Date: Tue, 15 Mar 2016 14:10:29 +0000
   4 Subject: [PATCH] bcm2835-sdhost: Workaround for "slow" sectors
   5
   6 Some cards have been seen to cause timeouts after certain sectors are
   7 read. This workaround enforces a minimum delay between the stop after
   8 reading one of those sectors and a subsequent data command.
   9
  10 Using CMD23 (SET_BLOCK_COUNT) avoids this problem, so good cards will
  11 not be penalised by this workaround.
  12
  13 Signed-off-by: Phil Elwell <phil@raspberrypi.org>
  14 ---
  15  drivers/mmc/host/bcm2835-sdhost.c | 50 +++++++++++++++++++++++++++++++++++----
  16  1 file changed, 46 insertions(+), 4 deletions(-)
  17
  18 --- a/drivers/mmc/host/bcm2835-sdhost.c
  19 +++ b/drivers/mmc/host/bcm2835-sdhost.c
  20 @@ -202,9 +202,12 @@ struct bcm2835_host {
  21         int                             max_delay;      /* maximum length of time spent waiting */
  22         struct timeval                  stop_time;      /* when the last stop was issued */
  23         u32                             delay_after_stop; /* minimum time between stop and subsequent data transfer */
  24 +       u32                             delay_after_this_stop; /* minimum time between this stop and subsequent data transfer */
  25         u32                             overclock_50;   /* frequency to use when 50MHz is requested (in MHz) */
  26         u32                             overclock;      /* Current frequency if overclocked, else zero */
  27         u32                             pio_limit;      /* Maximum block count for PIO (0 = always DMA) */
  28 +
  29 +       u32                             sectors;        /* Cached card size in sectors */
  30  };
  31
  32  #if ENABLE_LOG
  33 @@ -425,6 +428,7 @@ static void bcm2835_sdhost_reset_interna
  34         bcm2835_sdhost_set_power(host, true);
  35         mdelay(10);
  36         host->clock = 0;
  37 +       host->sectors = 0;
  38         bcm2835_sdhost_write(host, host->hcfg, SDHCFG);
  39         bcm2835_sdhost_write(host, host->cdiv, SDCDIV);
  40         mmiowb();
  41 @@ -880,6 +884,24 @@ static void bcm2835_sdhost_prepare_data(
  42         host->flush_fifo = 0;
  43         host->data->bytes_xfered = 0;
  44
  45 +       if (!host->sectors && host->mmc->card) {
  46 +               struct mmc_card *card = host->mmc->card;
  47 +               if (!mmc_card_sd(card) && mmc_card_blockaddr(card)) {
  48 +                       /*
  49 +                        * The EXT_CSD sector count is in number of 512 byte
  50 +                        * sectors.
  51 +                        */
  52 +                       host->sectors = card->ext_csd.sectors;
  53 +               } else {
  54 +                       /*
  55 +                        * The CSD capacity field is in units of read_blkbits.
  56 +                        * set_capacity takes units of 512 bytes.
  57 +                        */
  58 +                       host->sectors = card->csd.capacity <<
  59 +                               (card->csd.read_blkbits - 9);
  60 +               }
  61 +       }
  62 +
  63         if (!host->dma_desc) {
  64                 /* Use PIO */
  65                 int flags = SG_MITER_ATOMIC;
  66 @@ -989,7 +1011,7 @@ bool bcm2835_sdhost_send_command(struct
  67
  68         if (cmd->data) {
  69                 log_event("CMDD", cmd->data->blocks, cmd->data->blksz);
  70 -               if (host->delay_after_stop) {
  71 +               if (host->delay_after_this_stop) {
  72                         struct timeval now;
  73                         int time_since_stop;
  74                         do_gettimeofday(&now);
  75 @@ -998,12 +1020,32 @@ bool bcm2835_sdhost_send_command(struct
  76                                 /* Possibly less than one second */
  77                                 time_since_stop = time_since_stop * 1000000 +
  78                                         (now.tv_usec - host->stop_time.tv_usec);
  79 -                               if (time_since_stop < host->delay_after_stop)
  80 -                                       udelay(host->delay_after_stop -
  81 +                               if (time_since_stop <
  82 +                                   host->delay_after_this_stop)
  83 +                                       udelay(host->delay_after_this_stop -
  84                                                time_since_stop);
  85                         }
  86                 }
  87
  88 +               host->delay_after_this_stop = host->delay_after_stop;
  89 +               if ((cmd->data->flags & MMC_DATA_READ) && !host->use_sbc) {
  90 +                       /* See if read crosses one of the hazardous sectors */
  91 +                       u32 first_blk, last_blk;
  92 +
  93 +                       /* Intentionally include the following sector because
  94 +                          without CMD23/SBC the read may run on. */
  95 +                       first_blk = host->mrq->cmd->arg;
  96 +                       last_blk = first_blk + cmd->data->blocks;
  97 +
  98 +                       if (((last_blk >= (host->sectors - 64)) &&
  99 +                            (first_blk <= (host->sectors - 64))) ||
 100 +                           ((last_blk >= (host->sectors - 32)) &&
 101 +                            (first_blk <= (host->sectors - 32)))) {
 102 +                               host->delay_after_this_stop =
 103 +                                       max(250u, host->delay_after_stop);
 104 +                       }
 105 +               }
 106 +
 107                 if (cmd->data->flags & MMC_DATA_WRITE)
 108                         sdcmd |= SDCMD_WRITE_CMD;
 109                 if (cmd->data->flags & MMC_DATA_READ)
 110 @@ -1078,7 +1120,7 @@ static void bcm2835_sdhost_transfer_comp
 111                         if (!host->use_busy)
 112                                 bcm2835_sdhost_finish_command(host, NULL);
 113
 114 -                       if (host->delay_after_stop)
 115 +                       if (host->delay_after_this_stop)
 116                                 do_gettimeofday(&host->stop_time);
 117                 }
 118         } else {