target/linux/brcm2708/patches-4.4/0234-bcm2835-sdhost-Reset-the-clock-in-task-context.patch

   1 From d17f0605ff4b3197eb6667368adc07c5ca859679 Mon Sep 17 00:00:00 2001
   2 From: Phil Elwell <phil@raspberrypi.org>
   3 Date: Mon, 11 Apr 2016 12:50:58 +0100
   4 Subject: [PATCH] bcm2835-sdhost: Reset the clock in task context
   5
   6 Since reprogramming the clock can now involve a round-trip to the
   7 firmware it must not be done at atomic context, and a tasklet
   8 is not a task.
   9
  10 Signed-off-by: Phil Elwell <phil@raspberrypi.org>
  11 ---
  12  drivers/mmc/host/bcm2835-sdhost.c | 25 ++++++++++++++++++-------
  13  1 file changed, 18 insertions(+), 7 deletions(-)
  14
  15 --- a/drivers/mmc/host/bcm2835-sdhost.c
  16 +++ b/drivers/mmc/host/bcm2835-sdhost.c
  17 @@ -185,6 +185,7 @@ struct bcm2835_host {
  18
  19         unsigned int                    debug:1;                /* Enable debug output */
  20         unsigned int                    firmware_sets_cdiv:1;   /* Let the firmware manage the clock */
  21 +       unsigned int                    reset_clock:1;          /* Reset the clock fore the next request */
  22
  23         /*DMA part*/
  24         struct dma_chan                 *dma_chan_rxtx;         /* DMA channel for reads and writes */
  25 @@ -1505,6 +1506,7 @@ void bcm2835_sdhost_set_clock(struct bcm
  26  {
  27         int div = 0; /* Initialized for compiler warning */
  28         unsigned int input_clock = clock;
  29 +       unsigned long flags;
  30
  31         if (host->debug)
  32                 pr_info("%s: set_clock(%d)\n", mmc_hostname(host->mmc), clock);
  33 @@ -1544,13 +1546,17 @@ void bcm2835_sdhost_set_clock(struct bcm
  34                                       &msg, sizeof(msg));
  35
  36                 clock = max(msg[1], msg[2]);
  37 +               spin_lock_irqsave(&host->lock, flags);
  38         } else {
  39 +               spin_lock_irqsave(&host->lock, flags);
  40                 if (clock < 100000) {
  41                         /* Can't stop the clock, but make it as slow as
  42                          * possible to show willing
  43                          */
  44                         host->cdiv = SDCDIV_MAX_CDIV;
  45                         bcm2835_sdhost_write(host, host->cdiv, SDCDIV);
  46 +                       mmiowb();
  47 +                       spin_unlock_irqrestore(&host->lock, flags);
  48                         return;
  49                 }
  50
  51 @@ -1605,6 +1611,11 @@ void bcm2835_sdhost_set_clock(struct bcm
  52         bcm2835_sdhost_write(host, clock/2, SDTOUT);
  53
  54         host->mmc->actual_clock = clock;
  55 +       host->clock = input_clock;
  56 +       host->reset_clock = 0;
  57 +
  58 +       mmiowb();
  59 +       spin_unlock_irqrestore(&host->lock, flags);
  60  }
  61
  62  static void bcm2835_sdhost_request(struct mmc_host *mmc, struct mmc_request *mrq)
  63 @@ -1653,6 +1664,9 @@ static void bcm2835_sdhost_request(struc
  64             (mrq->data->blocks > host->pio_limit))
  65                 bcm2835_sdhost_prepare_dma(host, mrq->data);
  66
  67 +       if (host->reset_clock)
  68 +           bcm2835_sdhost_set_clock(host, host->clock);
  69 +
  70         spin_lock_irqsave(&host->lock, flags);
  71
  72         WARN_ON(host->mrq != NULL);
  73 @@ -1731,14 +1745,12 @@ static void bcm2835_sdhost_set_ios(struc
  74
  75         bcm2835_sdhost_write(host, host->hcfg, SDHCFG);
  76
  77 -       if (!ios->clock || ios->clock != host->clock) {
  78 -               bcm2835_sdhost_set_clock(host, ios->clock);
  79 -               host->clock = ios->clock;
  80 -       }
  81 -
  82         mmiowb();
  83
  84         spin_unlock_irqrestore(&host->lock, flags);
  85 +
  86 +       if (!ios->clock || ios->clock != host->clock)
  87 +               bcm2835_sdhost_set_clock(host, ios->clock);
  88  }
  89
  90  static struct mmc_host_ops bcm2835_sdhost_ops = {
  91 @@ -1810,7 +1822,7 @@ static void bcm2835_sdhost_tasklet_finis
  92                         host->overclock_50--;
  93                         pr_warn("%s: reducing overclock due to errors\n",
  94                                 mmc_hostname(host->mmc));
  95 -                       bcm2835_sdhost_set_clock(host,50*MHZ);
  96 +                       host->reset_clock = 1;
  97                         mrq->cmd->error = -EILSEQ;
  98                         mrq->cmd->retries = 1;
  99                 }
 100 @@ -1979,7 +1991,6 @@ static int bcm2835_sdhost_probe(struct p
 101         mmc->ops = &bcm2835_sdhost_ops;
 102         host = mmc_priv(mmc);
 103         host->mmc = mmc;
 104 -       host->cmd_quick_poll_retries = 0;
 105         host->pio_timeout = msecs_to_jiffies(500);
 106         host->pio_limit = 1;
 107         host->max_delay = 1; /* Warn if over 1ms */