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.
I submitted it earlier but it's now adapted to and tested with kernel
2.6.36-rc3.
In case SDIO is broken, it'll still try to detect SDMEM, also at different
freqs.
Signed-off-by: Hein Tibosch <hein_tibosch@xxxxxxxx>
---
diff -Nurp a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
--- a/drivers/mmc/core/core.c 2010-08-29 23:36:04.000000000 +0800
+++ b/drivers/mmc/core/core.c 2010-09-03 04:28:52.000000000 +0800
@@ -907,12 +907,7 @@ static void mmc_power_up(struct mmc_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);
@@ -1404,6 +1399,8 @@ void mmc_rescan(struct work_struct *work
u32 ocr;
int err;
unsigned long flags;
+ int i;
+ unsigned freqs[] = { 400000, 300000, 200000, 100000 };
spin_lock_irqsave(&host->lock, flags);
@@ -1443,55 +1440,64 @@ 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)
+ goto out;
+ else
+ host->f_init = host->f_min;
- mmc_send_if_cond(host, host->ocr_avail);
+ printk ("mmc_rescan: trying %u Hz\n", host->f_init);
+ 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 -Nurp a/include/linux/mmc/host.h b/include/linux/mmc/host.h
--- a/include/linux/mmc/host.h 2010-08-29 23:36:04.000000000 +0800
+++ b/include/linux/mmc/host.h 2010-09-03 00:52:48.000000000 +0800
@@ -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;
---
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