target/linux/brcm2708/patches-4.4/0222-bcm2835-sdhost-Precalc-divisors-and-overclocks.patch

   1 From d2b23892c9f7b04b68280889bea7823ba555b325 Mon Sep 17 00:00:00 2001
   2 From: Phil Elwell <phil@raspberrypi.org>
   3 Date: Thu, 31 Mar 2016 15:44:53 +0100
   4 Subject: [PATCH 222/304] bcm2835-sdhost: Precalc divisors and overclocks
   5
   6 Recalculating the clock divisors when the core clock changes is wasteful
   7 and makes it harder to manage the overclock settings. Instead,
   8 precalculate them and only report significant changes.
   9
  10 Signed-off-by: Phil Elwell <phil@raspberrypi.org>
  11 ---
  12  drivers/mmc/host/bcm2835-sdhost.c | 152 ++++++++++++++++++++++----------------
  13  1 file changed, 88 insertions(+), 64 deletions(-)
  14
  15 --- a/drivers/mmc/host/bcm2835-sdhost.c
  16 +++ b/drivers/mmc/host/bcm2835-sdhost.c
  17 @@ -154,12 +154,15 @@ struct bcm2835_host {
  18         u32                     pio_timeout;    /* In jiffies */
  19
  20         int                     clock;          /* Current clock speed */
  21 +       int                     clocks[2];
  22
  23         bool                    slow_card;      /* Force 11-bit divisor */
  24
  25         unsigned int            max_clk;        /* Max src clock freq */
  26 -       unsigned int            min_clk;        /* Min src clock freq */
  27 -       unsigned int            cur_clk;        /* Current src clock freq */
  28 +       unsigned int            src_clks[2];    /* Min/max src clock freqs */
  29 +       unsigned int            cur_clk_idx;    /* Index of current clock */
  30 +       unsigned int            next_clk_idx;   /* Next clock index */
  31 +       unsigned int            cdivs[2];
  32
  33         struct tasklet_struct   finish_tasklet; /* Tasklet structures */
  34
  35 @@ -213,7 +216,7 @@ struct bcm2835_host {
  36         u32                             delay_after_stop; /* minimum time between stop and subsequent data transfer */
  37         u32                             delay_after_this_stop; /* minimum time between this stop and subsequent data transfer */
  38         u32                             overclock_50;   /* frequency to use when 50MHz is requested (in MHz) */
  39 -       u32                             overclock;      /* Current frequency if overclocked, else zero */
  40 +       u32                             prev_overclock_50;
  41         u32                             pio_limit;      /* Maximum block count for PIO (0 = always DMA) */
  42
  43         u32                             sectors;        /* Cached card size in sectors */
  44 @@ -1509,10 +1512,35 @@ static irqreturn_t bcm2835_sdhost_irq(in
  45         return result;
  46  }
  47
  48 +static void bcm2835_sdhost_select_clock(struct bcm2835_host *host, int idx)
  49 +{
  50 +       unsigned int clock = host->clocks[idx];
  51 +       unsigned int cdiv = host->cdivs[idx];
  52 +
  53 +       host->mmc->actual_clock = clock;
  54 +       host->ns_per_fifo_word = (1000000000/clock) *
  55 +               ((host->mmc->caps & MMC_CAP_4_BIT_DATA) ? 8 : 32);
  56 +
  57 +       host->cdiv = cdiv;
  58 +       bcm2835_sdhost_write(host, host->cdiv, SDCDIV);
  59 +
  60 +       /* Set the timeout to 500ms */
  61 +       bcm2835_sdhost_write(host, clock/2, SDTOUT);
  62 +
  63 +       host->cur_clk_idx = host->next_clk_idx = idx;
  64 +
  65 +       if (host->debug)
  66 +               pr_info("%s: clock=%d -> src_clk=%d, cdiv=%x (actual %d)\n",
  67 +                       mmc_hostname(host->mmc), host->clock,
  68 +                       host->src_clks[idx], host->cdiv,
  69 +                       host->mmc->actual_clock);
  70 +}
  71 +
  72  void bcm2835_sdhost_set_clock(struct bcm2835_host *host)
  73  {
  74         int div = 0; /* Initialized for compiler warning */
  75         unsigned int clock = host->clock;
  76 +       int clk_idx;
  77
  78         if (host->debug)
  79                 pr_info("%s: set_clock(%d)\n", mmc_hostname(host->mmc), clock);
  80 @@ -1553,53 +1581,45 @@ void bcm2835_sdhost_set_clock(struct bcm
  81             return;
  82         }
  83
  84 -       div = host->cur_clk / clock;
  85 -       if (div < 2)
  86 -               div = 2;
  87 -       if ((host->cur_clk / div) > clock)
  88 -               div++;
  89 -       div -= 2;
  90 -
  91 -       if (div > SDCDIV_MAX_CDIV)
  92 -           div = SDCDIV_MAX_CDIV;
  93 -
  94 -       clock = host->cur_clk / (div + 2);
  95 -       host->mmc->actual_clock = clock;
  96 -
  97 -       /* Calibrate some delays */
  98 -
  99 -       host->ns_per_fifo_word = (1000000000/clock) *
 100 -               ((host->mmc->caps & MMC_CAP_4_BIT_DATA) ? 8 : 32);
 101 +       /* Calculate the clock divisors */
 102 +       for (clk_idx = 0; clk_idx <= host->variable_clock; clk_idx++)
 103 +       {
 104 +               unsigned int cur_clk = host->src_clks[clk_idx];
 105 +               unsigned int actual_clock;
 106
 107 -       if (clock > host->clock) {
 108 -               /* Save the closest value, to make it easier
 109 -                  to reduce in the event of error */
 110 -               host->overclock_50 = (clock/MHZ);
 111 -
 112 -               if (clock != host->overclock) {
 113 -                       pr_warn("%s: overclocking to %dHz\n",
 114 -                               mmc_hostname(host->mmc), clock);
 115 -                       host->overclock = clock;
 116 +               div = cur_clk / clock;
 117 +               if (div < 2)
 118 +                       div = 2;
 119 +               if ((cur_clk / div) > clock)
 120 +                       div++;
 121 +               div -= 2;
 122 +
 123 +               if (div > SDCDIV_MAX_CDIV)
 124 +                       div = SDCDIV_MAX_CDIV;
 125 +               actual_clock = cur_clk / (div + 2);
 126 +
 127 +               host->cdivs[clk_idx] = div;
 128 +               host->clocks[clk_idx] = actual_clock;
 129 +
 130 +               if (host->overclock_50 != host->prev_overclock_50) {
 131 +                       const char *clk_name = "";
 132 +                       if (host->variable_clock)
 133 +                               clk_name = clk_idx ? " (turbo)" : " (normal)";
 134 +                       if (actual_clock > host->clock)
 135 +                               pr_info("%s: overclocking to %dHz%s\n",
 136 +                                       mmc_hostname(host->mmc),
 137 +                                       actual_clock, clk_name);
 138 +                       else if ((host->overclock_50 < 50) && (clk_idx == 0))
 139 +                               pr_info("%s: cancelling overclock%s\n",
 140 +                                       mmc_hostname(host->mmc),
 141 +                                       host->variable_clock ? "s" : "");
 142                 }
 143         }
 144 -       else if (host->overclock)
 145 -       {
 146 -               host->overclock = 0;
 147 -               if (clock == 50 * MHZ)
 148 -                       pr_warn("%s: cancelling overclock\n",
 149 -                               mmc_hostname(host->mmc));
 150 -       }
 151
 152 -       host->cdiv = div;
 153 -       bcm2835_sdhost_write(host, host->cdiv, SDCDIV);
 154 +       if (host->clock == 50*MHZ)
 155 +               host->prev_overclock_50 = host->overclock_50;
 156
 157 -       /* Set the timeout to 500ms */
 158 -       bcm2835_sdhost_write(host, host->mmc->actual_clock/2, SDTOUT);
 159 -
 160 -       if (host->debug)
 161 -               pr_info("%s: clock=%d -> cur_clk=%d, cdiv=%x (actual clock %d)\n",
 162 -                       mmc_hostname(host->mmc), host->clock,
 163 -                       host->cur_clk, host->cdiv, host->mmc->actual_clock);
 164 +       bcm2835_sdhost_select_clock(host, host->cur_clk_idx);
 165  }
 166
 167  static void bcm2835_sdhost_request(struct mmc_host *mmc, struct mmc_request *mrq)
 168 @@ -1657,6 +1677,9 @@ static void bcm2835_sdhost_request(struc
 169
 170         spin_lock_irqsave(&host->lock, flags);
 171
 172 +       if (host->next_clk_idx != host->cur_clk_idx)
 173 +               bcm2835_sdhost_select_clock(host, host->next_clk_idx);
 174 +
 175         WARN_ON(host->mrq != NULL);
 176         host->mrq = mrq;
 177
 178 @@ -1719,11 +1742,7 @@ static int bcm2835_sdhost_cpufreq_callba
 179                                 return NOTIFY_BAD;
 180                         break;
 181                 case CPUFREQ_POSTCHANGE:
 182 -                       if (freq->new > freq->old)
 183 -                               host->cur_clk = host->max_clk;
 184 -                       else
 185 -                               host->cur_clk = host->min_clk;
 186 -                       bcm2835_sdhost_set_clock(host);
 187 +                       host->next_clk_idx = (freq->new > freq->old);
 188                         up(&host->cpufreq_semaphore);
 189                         break;
 190                 default:
 191 @@ -1763,8 +1782,11 @@ static void bcm2835_sdhost_set_ios(struc
 192                         ios->clock, ios->power_mode, ios->bus_width,
 193                         ios->timing, ios->signal_voltage, ios->drv_type);
 194
 195 -       if (ios->clock && !host->cur_clk)
 196 -               host->cur_clk = get_core_clock(RPI_FIRMWARE_GET_CLOCK_RATE);
 197 +       if (ios->clock && (host->cur_clk_idx == -1)) {
 198 +               unsigned int cur_clk =
 199 +                       get_core_clock(RPI_FIRMWARE_GET_CLOCK_RATE);
 200 +               host->cur_clk_idx = (cur_clk == host->src_clks[0]) ? 0 : 1;
 201 +       }
 202
 203         spin_lock_irqsave(&host->lock, flags);
 204
 205 @@ -1854,11 +1876,12 @@ static void bcm2835_sdhost_tasklet_finis
 206
 207         /* Drop the overclock after any data corruption, or after any
 208            error overclocked */
 209 -       if (host->overclock) {
 210 +       if (host->clock > 50*MHZ) {
 211                 if ((mrq->cmd && mrq->cmd->error) ||
 212                     (mrq->data && mrq->data->error) ||
 213                     (mrq->stop && mrq->stop->error)) {
 214 -                       host->overclock_50--;
 215 +                       host->overclock_50 = (host->clock/MHZ) - 1;
 216 +
 217                         pr_warn("%s: reducing overclock due to errors\n",
 218                                 mmc_hostname(host->mmc));
 219                         bcm2835_sdhost_set_clock(host);
 220 @@ -2022,7 +2045,7 @@ static int bcm2835_sdhost_probe(struct p
 221         struct bcm2835_host *host;
 222         struct mmc_host *mmc;
 223         const __be32 *addr;
 224 -       unsigned int max_clk;
 225 +       unsigned int max_clk, min_clk;
 226         int ret;
 227
 228         pr_debug("bcm2835_sdhost_probe\n");
 229 @@ -2128,12 +2151,8 @@ static int bcm2835_sdhost_probe(struct p
 230         else
 231                 mmc->caps |= MMC_CAP_4_BIT_DATA;
 232
 233 -       ret = bcm2835_sdhost_add_host(host);
 234 -       if (ret)
 235 -               goto err;
 236 -
 237         /* Query the core clock frequencies */
 238 -       host->min_clk = get_core_clock(RPI_FIRMWARE_GET_MIN_CLOCK_RATE);
 239 +       min_clk = get_core_clock(RPI_FIRMWARE_GET_MIN_CLOCK_RATE);
 240         max_clk = get_core_clock(RPI_FIRMWARE_GET_MAX_CLOCK_RATE);
 241         if (max_clk != host->max_clk) {
 242                 pr_warn("%s: Expected max clock %d, found %d\n",
 243 @@ -2141,19 +2160,24 @@ static int bcm2835_sdhost_probe(struct p
 244                 host->max_clk = max_clk;
 245         }
 246
 247 -       if (host->min_clk != host->max_clk) {
 248 +       host->src_clks[0] = min_clk;
 249 +       host->cur_clk_idx = -1;
 250 +       if (max_clk != min_clk) {
 251 +               host->src_clks[1] = max_clk;
 252                 host->cpufreq_nb.notifier_call =
 253                         bcm2835_sdhost_cpufreq_callback;
 254                 sema_init(&host->cpufreq_semaphore, 1);
 255                 cpufreq_register_notifier(&host->cpufreq_nb,
 256                                           CPUFREQ_TRANSITION_NOTIFIER);
 257                 host->variable_clock = 1;
 258 -               host->cur_clk = 0; /* Get this later */
 259         } else {
 260                 host->variable_clock = 0;
 261 -               host->cur_clk = host->max_clk;
 262         }
 263
 264 +       ret = bcm2835_sdhost_add_host(host);
 265 +       if (ret)
 266 +               goto err;
 267 +
 268         platform_set_drvdata(pdev, host);
 269
 270         pr_debug("bcm2835_sdhost_probe -> OK\n");