queue-5.0/mmc-alcor-don-t-write-data-before-command-has-completed.patch

   1 From 157c99c5a2956a9ab1ae12de0136a2d8a1b1a307 Mon Sep 17 00:00:00 2001
   2 From: Daniel Drake <drake@endlessm.com>
   3 Date: Tue, 26 Mar 2019 15:04:14 +0800
   4 Subject: mmc: alcor: don't write data before command has completed
   5
   6 From: Daniel Drake <drake@endlessm.com>
   7
   8 commit 157c99c5a2956a9ab1ae12de0136a2d8a1b1a307 upstream.
   9
  10 The alcor driver is setting up data transfer and submitting the associated
  11 MMC command at the same time. While this works most of the time, it
  12 occasionally causes problems upon write.
  13
  14 In the working case, after setting up the data transfer and submitting
  15 the MMC command, an interrupt comes in a moment later with CMD_END and
  16 WRITE_BUF_RDY bits set. The data transfer then happens without problem.
  17
  18 However, on occasion, the interrupt that arrives at that point only
  19 has WRITE_BUF_RDY set. The hardware notifies that it's ready to write
  20 data, but the associated MMC command is still running. Regardless, the
  21 driver was proceeding to write data immediately, and that would then cause
  22 another interrupt indicating data CRC error, and the write would fail.
  23
  24 Additionally, the transfer setup function alcor_trigger_data_transfer()
  25 was being called 3 times for each write operation, which was confusing
  26 and may be contributing to this issue.
  27
  28 Solve this by tweaking the driver behaviour to follow the sequence observed
  29 in the original ampe_stor vendor driver:
  30  1. When starting request handling, write 0 to DATA_XFER_CTRL
  31  2. Submit the command
  32  3. Wait for CMD_END interrupt and then trigger data transfer
  33  4. For the PIO case, trigger the next step of the data transfer only
  34     upon the following DATA_END interrupt, which occurs after the block has
  35     been written.
  36
  37 I confirmed that the read path still works (DMA & PIO) and also now
  38 presents more consistency with the operations performed by ampe_stor.
  39
  40 Signed-off-by: Daniel Drake <drake@endlessm.com>
  41 Fixes: c5413ad815a6 ("mmc: add new Alcor Micro Cardreader SD/MMC driver")
  42 Cc: stable@vger.kernel.org
  43 Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
  44 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  45
  46 ---
  47  drivers/mmc/host/alcor.c |   34 +++++++++++++---------------------
  48  1 file changed, 13 insertions(+), 21 deletions(-)
  49
  50 --- a/drivers/mmc/host/alcor.c
  51 +++ b/drivers/mmc/host/alcor.c
  52 @@ -48,7 +48,6 @@ struct alcor_sdmmc_host {
  53         struct mmc_command *cmd;
  54         struct mmc_data *data;
  55         unsigned int dma_on:1;
  56 -       unsigned int early_data:1;
  57
  58         struct mutex cmd_mutex;
  59
  60 @@ -144,8 +143,7 @@ static void alcor_data_set_dma(struct al
  61         host->sg_count--;
  62  }
  63
  64 -static void alcor_trigger_data_transfer(struct alcor_sdmmc_host *host,
  65 -                                       bool early)
  66 +static void alcor_trigger_data_transfer(struct alcor_sdmmc_host *host)
  67  {
  68         struct alcor_pci_priv *priv = host->alcor_pci;
  69         struct mmc_data *data = host->data;
  70 @@ -155,13 +153,6 @@ static void alcor_trigger_data_transfer(
  71                 ctrl |= AU6601_DATA_WRITE;
  72
  73         if (data->host_cookie == COOKIE_MAPPED) {
  74 -               if (host->early_data) {
  75 -                       host->early_data = false;
  76 -                       return;
  77 -               }
  78 -
  79 -               host->early_data = early;
  80 -
  81                 alcor_data_set_dma(host);
  82                 ctrl |= AU6601_DATA_DMA_MODE;
  83                 host->dma_on = 1;
  84 @@ -231,6 +222,7 @@ static void alcor_prepare_sg_miter(struc
  85  static void alcor_prepare_data(struct alcor_sdmmc_host *host,
  86                                struct mmc_command *cmd)
  87  {
  88 +       struct alcor_pci_priv *priv = host->alcor_pci;
  89         struct mmc_data *data = cmd->data;
  90
  91         if (!data)
  92 @@ -248,7 +240,7 @@ static void alcor_prepare_data(struct al
  93         if (data->host_cookie != COOKIE_MAPPED)
  94                 alcor_prepare_sg_miter(host);
  95
  96 -       alcor_trigger_data_transfer(host, true);
  97 +       alcor_write8(priv, 0, AU6601_DATA_XFER_CTRL);
  98  }
  99
 100  static void alcor_send_cmd(struct alcor_sdmmc_host *host,
 101 @@ -435,7 +427,7 @@ static int alcor_cmd_irq_done(struct alc
 102         if (!host->data)
 103                 return false;
 104
 105 -       alcor_trigger_data_transfer(host, false);
 106 +       alcor_trigger_data_transfer(host);
 107         host->cmd = NULL;
 108         return true;
 109  }
 110 @@ -456,7 +448,7 @@ static void alcor_cmd_irq_thread(struct
 111         if (!host->data)
 112                 alcor_request_complete(host, 1);
 113         else
 114 -               alcor_trigger_data_transfer(host, false);
 115 +               alcor_trigger_data_transfer(host);
 116         host->cmd = NULL;
 117  }
 118
 119 @@ -487,15 +479,9 @@ static int alcor_data_irq_done(struct al
 120                 break;
 121         case AU6601_INT_READ_BUF_RDY:
 122                 alcor_trf_block_pio(host, true);
 123 -               if (!host->blocks)
 124 -                       break;
 125 -               alcor_trigger_data_transfer(host, false);
 126                 return 1;
 127         case AU6601_INT_WRITE_BUF_RDY:
 128                 alcor_trf_block_pio(host, false);
 129 -               if (!host->blocks)
 130 -                       break;
 131 -               alcor_trigger_data_transfer(host, false);
 132                 return 1;
 133         case AU6601_INT_DMA_END:
 134                 if (!host->sg_count)
 135 @@ -508,8 +494,14 @@ static int alcor_data_irq_done(struct al
 136                 break;
 137         }
 138
 139 -       if (intmask & AU6601_INT_DATA_END)
 140 -               return 0;
 141 +       if (intmask & AU6601_INT_DATA_END) {
 142 +               if (!host->dma_on && host->blocks) {
 143 +                       alcor_trigger_data_transfer(host);
 144 +                       return 1;
 145 +               } else {
 146 +                       return 0;
 147 +               }
 148 +       }
 149
 150         return 1;
 151  }