mmc: Make ID freq configurable

In the latest releases of the mmc driver, the freq during initialization
is set to a fixed 400 Khz.  This was reportedly too fast for several
users.  As there doesn't seem to be an ideal frequency
which-works-for-all, Pierre suggested to let the driver try several
frequencies.

This patch implements that idea. It will try mmc-initialization using
several frequencies from an array 400, 300, 200 and 100.

In case SDIO is broken, it'll still try to detect SDMEM, also at different
freqs.

Signed-off-by: Hein Tibosch <hein_tibosch@yahoo.es>
Cc: Pierre Ossman <pierre@ossman.eu>
Reviewed-by: Chris Ball <cjb@laptop.org>
Tested-by: Chris Ball <cjb@laptop.org>
Cc: Ben Nizette <bn@niasdigital.com>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Adrian Hunter <adrian.hunter@nokia.com>
Cc: Matt Fleming <matt@console-pimps.org>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Chris Ball <cjb@laptop.org>

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index ab4446c428be50a68f8d3387f1fe58347db83d45..222466df66ffd6819129810e7696ccb861209125 100644 (file)
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -908,12 +908,7 @@ static void mmc_power_up(struct mmc_host *host)
         */
        mmc_delay(10);
 
-       if (host->f_min > 400000) {
-               pr_warning("%s: Minimum clock frequency too high for "
-                               "identification mode\n", mmc_hostname(host));
-               host->ios.clock = host->f_min;
-       } else
-               host->ios.clock = 400000;
+       host->ios.clock = host->f_init;
 
        host->ios.power_mode = MMC_POWER_ON;
        mmc_set_ios(host);
@@ -1405,6 +1400,8 @@ void mmc_rescan(struct work_struct *work)
        u32 ocr;
        int err;
        unsigned long flags;
+       int i;
+       const unsigned freqs[] = { 400000, 300000, 200000, 100000 };
 
        spin_lock_irqsave(&host->lock, flags);
 
@@ -1444,55 +1441,70 @@ void mmc_rescan(struct work_struct *work)
        if (host->ops->get_cd && host->ops->get_cd(host) == 0)
                goto out;
 
-       mmc_claim_host(host);
+       for (i = 0; i < ARRAY_SIZE(freqs); i++) {
+               mmc_claim_host(host);
 
-       mmc_power_up(host);
-       sdio_reset(host);
-       mmc_go_idle(host);
+               if (freqs[i] >= host->f_min)
+                       host->f_init = freqs[i];
+               else if (!i || freqs[i-1] > host->f_min)
+                       host->f_init = host->f_min;
+               else {
+                       mmc_release_host(host);
+                       goto out;
+               }
+               pr_info("%s: %s: trying to init card at %u Hz\n",
+                       mmc_hostname(host), __func__, host->f_init);
 
-       mmc_send_if_cond(host, host->ocr_avail);
+               mmc_power_up(host);
+               sdio_reset(host);
+               mmc_go_idle(host);
 
-       /*
-        * First we search for SDIO...
-        */
-       err = mmc_send_io_op_cond(host, 0, &ocr);
-       if (!err) {
-               if (mmc_attach_sdio(host, ocr)) {
-                       mmc_claim_host(host);
-                       /* try SDMEM (but not MMC) even if SDIO is broken */
-                       if (mmc_send_app_op_cond(host, 0, &ocr))
-                               goto out_fail;
+               mmc_send_if_cond(host, host->ocr_avail);
 
+               /*
+                * First we search for SDIO...
+                */
+               err = mmc_send_io_op_cond(host, 0, &ocr);
+               if (!err) {
+                       if (mmc_attach_sdio(host, ocr)) {
+                               mmc_claim_host(host);
+                               /*
+                                * Try SDMEM (but not MMC) even if SDIO
+                                * is broken.
+                                */
+                               if (mmc_send_app_op_cond(host, 0, &ocr))
+                                       goto out_fail;
+
+                               if (mmc_attach_sd(host, ocr))
+                                       mmc_power_off(host);
+                       }
+                       goto out;
+               }
+
+               /*
+                * ...then normal SD...
+                */
+               err = mmc_send_app_op_cond(host, 0, &ocr);
+               if (!err) {
                        if (mmc_attach_sd(host, ocr))
                                mmc_power_off(host);
+                       goto out;
                }
-               goto out;
-       }
 
-       /*
-        * ...then normal SD...
-        */
-       err = mmc_send_app_op_cond(host, 0, &ocr);
-       if (!err) {
-               if (mmc_attach_sd(host, ocr))
-                       mmc_power_off(host);
-               goto out;
-       }
-
-       /*
-        * ...and finally MMC.
-        */
-       err = mmc_send_op_cond(host, 0, &ocr);
-       if (!err) {
-               if (mmc_attach_mmc(host, ocr))
-                       mmc_power_off(host);
-               goto out;
-       }
+               /*
+                * ...and finally MMC.
+                */
+               err = mmc_send_op_cond(host, 0, &ocr);
+               if (!err) {
+                       if (mmc_attach_mmc(host, ocr))
+                               mmc_power_off(host);
+                       goto out;
+               }
 
 out_fail:
-       mmc_release_host(host);
-       mmc_power_off(host);
-
+               mmc_release_host(host);
+               mmc_power_off(host);
+       }
 out:
        if (host->caps & MMC_CAP_NEEDS_POLL)
                mmc_schedule_delayed_work(&host->detect, HZ);

diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 2e0fe623df90f4f657567f78c1e1e867ec102a46..20be040649a9a6188010c479831e110b6e98b381 100644 (file)
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -123,6 +123,7 @@ struct mmc_host {
        const struct mmc_host_ops *ops;
        unsigned int            f_min;
        unsigned int            f_max;
+       unsigned int            f_init;
        u32                     ocr_avail;
        struct notifier_block   pm_notify;