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mmc: core: Do regular power cycle when lacking eMMC HW reset support 

The eMMC HW reset may be implemented either via the host ops ->hw_reset()
callback or through DT and the eMMC pwrseq. Additionally some eMMC cards
don't support HW reset.

To allow a reset to be done for the different combinations of mmc hosts
and eMMC/MMC cards, let's implement a fallback via trying a regular power
cycle. This improves the mmc block layer retry mechanism of failing I/O
requests.

Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
[Ulf: Rewrote changelog]
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
This commit is contained in:
Gwendal Grignou 2016-04-01 16:04:22 -07:00 committed by Ulf Hansson
parent 6aef2eecc4
commit 4e6c71788d
2 changed files with 14 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
drivers/mmc/core/core.c
View File

@ -2456,8 +2456,9 @@ int mmc_hw_reset(struct mmc_host *host)
ret = host->bus_ops->reset(host);
mmc_bus_put(host);
if (ret != -EOPNOTSUPP)
pr_warn("%s: tried to reset card\n", mmc_hostname(host));
if (ret)
pr_warn("%s: tried to reset card, got error %d\n",
mmc_hostname(host), ret);
return ret;
}

16
drivers/mmc/core/mmc.c
View File

@ -1957,19 +1957,17 @@ static int mmc_reset(struct mmc_host *host)
{
struct mmc_card *card = host->card;
if (!(host->caps & MMC_CAP_HW_RESET) || !host->ops->hw_reset)
return -EOPNOTSUPP;
if (!mmc_can_reset(card))
return -EOPNOTSUPP;
if ((host->caps & MMC_CAP_HW_RESET) && host->ops->hw_reset &&
mmc_can_reset(card)) {
/* If the card accept RST_n signal, send it. */
mmc_set_clock(host, host->f_init);
host->ops->hw_reset(host);
/* Set initial state and call mmc_set_ios */
mmc_set_initial_state(host);
} else {
/* Do a brute force power cycle */
mmc_power_cycle(host, card->ocr);
}
return mmc_init_card(host, card->ocr, card);
}