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>

1 files changed, 57 insertions, 45 deletions

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index ab4446c428be..222466df66ff 100644
--- 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);