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 <[email protected]> --- 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; --- -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
