target/linux/generic/pending-5.15/350-mips-bmips-BCM6358-disable-RAC-flush-for-TP1.patch

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  64 From: =?utf-8?q?=C3=81lvaro_Fern=C3=A1ndez_Rojas?=  <noltari@gmail.com>
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  69 Subject: [PATCH v3] mips: bmips: BCM6358: disable RAC flush for TP1
  70 Date: Fri, 17 Mar 2023 11:20:04 +0100
  71 Message-Id: <20230317102004.235879-1-noltari@gmail.com>
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  79
  80 RAC flush causes kernel panics on BCM6358 with EHCI/OHCI when booting from TP1:
  81 [    3.881739] usb 1-1: new high-speed USB device number 2 using ehci-platform
  82 [    3.895011] Reserved instruction in kernel code[#1]:
  83 [    3.900113] CPU: 0 PID: 1 Comm: init Not tainted 5.10.16 #0
  84 [    3.905829] $ 0   : 00000000 10008700 00000000 77d94060
  85 [    3.911238] $ 4   : 7fd1f088 00000000 81431cac 81431ca0
  86 [    3.916641] $ 8   : 00000000 ffffefff 8075cd34 00000000
  87 [    3.922043] $12   : 806f8d40 f3e812b7 00000000 000d9aaa
  88 [    3.927446] $16   : 7fd1f068 7fd1f080 7ff559b8 81428470
  89 [    3.932848] $20   : 00000000 00000000 55590000 77d70000
  90 [    3.938251] $24   : 00000018 00000010
  91 [    3.943655] $28   : 81430000 81431e60 81431f28 800157fc
  92 [    3.949058] Hi    : 00000000
  93 [    3.952013] Lo    : 00000000
  94 [    3.955019] epc   : 80015808 setup_sigcontext+0x54/0x24c
  95 [    3.960464] ra    : 800157fc setup_sigcontext+0x48/0x24c
  96 [    3.965913] Status: 10008703 KERNEL EXL IE
  97 [    3.970216] Cause : 00800028 (ExcCode 0a)
  98 [    3.974340] PrId  : 0002a010 (Broadcom BMIPS4350)
  99 [    3.979170] Modules linked in: ohci_platform ohci_hcd fsl_mph_dr_of ehci_platform ehci_fsl ehci_hcd gpio_button_hotplug usbcore nls_base usb_common
 100 [    3.992907] Process init (pid: 1, threadinfo=(ptrval), task=(ptrval), tls=77e22ec8)
 101 [    4.000776] Stack : 81431ef4 7fd1f080 81431f28 81428470 7fd1f068 81431edc 7ff559b8 81428470
 102 [    4.009467]         81431f28 7fd1f080 55590000 77d70000 77d5498c 80015c70 806f0000 8063ae74
 103 [    4.018149]         08100002 81431f28 0000000a 08100002 81431f28 0000000a 77d6b418 00000003
 104 [    4.026831]         ffffffff 80016414 80080734 81431ecc 81431ecc 00000001 00000000 04000000
 105 [    4.035512]         77d54874 00000000 00000000 00000000 00000000 00000012 00000002 00000000
 106 [    4.044196]         ...
 107 [    4.046706] Call Trace:
 108 [    4.049238] [<80015808>] setup_sigcontext+0x54/0x24c
 109 [    4.054356] [<80015c70>] setup_frame+0xdc/0x124
 110 [    4.059015] [<80016414>] do_notify_resume+0x1dc/0x288
 111 [    4.064207] [<80011b50>] work_notifysig+0x10/0x18
 112 [    4.069036]
 113 [    4.070538] Code: 8fc300b4  00001025  26240008 <ac820000> ac830004  3c048063  0c0228aa  24846a00  26240010
 114 [    4.080686]
 115 [    4.082517] ---[ end trace 22a8edb41f5f983b ]---
 116 [    4.087374] Kernel panic - not syncing: Fatal exception
 117 [    4.092753] Rebooting in 1 seconds..
 118
 119 Because the bootloader (CFE) is not initializing the Read-ahead cache properly
 120 on the second thread (TP1). Since the RAC was not initialized properly, we
 121 should avoid flushing it at the risk of corrupting the instruction stream as
 122 seen in the trace above.
 123
 124 Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
 125 ---
 126  v3: add changes suggested by Florian:
 127    - Switch to a bool and remove unneeded initialization.
 128    - Remove if from bcm6358_quirks().
 129    - Improve commit description and bcm6358_quirks() comment.
 130  v2: check if we're running on TP1 and invert logic.
 131
 132  arch/mips/bmips/dma.c   | 5 +++++
 133  arch/mips/bmips/setup.c | 8 ++++++++
 134  2 files changed, 13 insertions(+)
 135
 136 --- a/arch/mips/bmips/dma.c
 137 +++ b/arch/mips/bmips/dma.c
 138 @@ -64,6 +64,8 @@ phys_addr_t dma_to_phys(struct device *d
 139         return dma_addr;
 140  }
 141
 142 +bool bmips_rac_flush_disable;
 143 +
 144  void arch_sync_dma_for_cpu_all(void)
 145  {
 146         void __iomem *cbr = BMIPS_GET_CBR();
 147 @@ -74,6 +76,9 @@ void arch_sync_dma_for_cpu_all(void)
 148             boot_cpu_type() != CPU_BMIPS4380)
 149                 return;
 150
 151 +       if (unlikely(bmips_rac_flush_disable))
 152 +               return;
 153 +
 154         /* Flush stale data out of the readahead cache */
 155         cfg = __raw_readl(cbr + BMIPS_RAC_CONFIG);
 156         __raw_writel(cfg | 0x100, cbr + BMIPS_RAC_CONFIG);
 157 --- a/arch/mips/bmips/setup.c
 158 +++ b/arch/mips/bmips/setup.c
 159 @@ -34,6 +34,8 @@
 160  #define REG_BCM6328_OTP                ((void __iomem *)CKSEG1ADDR(0x1000062c))
 161  #define BCM6328_TP1_DISABLED   BIT(9)
 162
 163 +extern bool bmips_rac_flush_disable;
 164 +
 165  static const unsigned long kbase = VMLINUX_LOAD_ADDRESS & 0xfff00000;
 166
 167  struct bmips_quirk {
 168 @@ -103,6 +105,12 @@ static void bcm6358_quirks(void)
 169          * disable SMP for now
 170          */
 171         bmips_smp_enabled = 0;
 172 +
 173 +       /*
 174 +        * RAC flush causes kernel panics on BCM6358 when booting from TP1
 175 +        * because the bootloader is not initializing it properly.
 176 +        */
 177 +       bmips_rac_flush_disable = !!(read_c0_brcm_cmt_local() & (1 << 31));
 178  }
 179
 180  static void bcm6368_quirks(void)