diff options
| author | Faiz Abbas <faiz_abbas@ti.com> | 2020-08-25 22:30:15 +0530 |
|---|---|---|
| committer | Ulf Hansson <ulf.hansson@linaro.org> | 2020-09-07 09:11:30 +0200 |
| commit | 7ca0f166f5b211f89fde9cf02357403e6f9715bc (patch) | |
| tree | 08e8a047e05596e9f7f49e686fd7aa6bb4bcae3f /drivers/mmc | |
| parent | d425e42d600849ed81bca4e407a09f2555405ec7 (diff) | |
mmc: sdhci_am654: Add workaround for card detect debounce timer
There is a one time delay because of a card detect debounce timer in the
controller IP. This timer runs as soon as power is applied to the module
regardless of whether a card is present or not and any writes to
SDHCI_POWER_ON will return 0 before it expires. This timeout has been
measured to be about 1 second in am654x and j721e.
Write-and-read-back in a loop on SDHCI_POWER_ON for a maximum of
1.5 seconds to make sure that the controller actually powers on.
Signed-off-by: Faiz Abbas <faiz_abbas@ti.com>
Link: https://lore.kernel.org/r/20200825170015.32285-1-faiz_abbas@ti.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Diffstat (limited to 'drivers/mmc')
| -rw-r--r-- | drivers/mmc/host/sdhci_am654.c | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/drivers/mmc/host/sdhci_am654.c b/drivers/mmc/host/sdhci_am654.c index 0f3ed716d3d2..c5f47197d177 100644 --- a/drivers/mmc/host/sdhci_am654.c +++ b/drivers/mmc/host/sdhci_am654.c @@ -6,6 +6,7 @@ * */ #include <linux/clk.h> +#include <linux/iopoll.h> #include <linux/of.h> #include <linux/module.h> #include <linux/pm_runtime.h> @@ -272,9 +273,19 @@ static void sdhci_j721e_4bit_set_clock(struct sdhci_host *host, sdhci_set_clock(host, clock); } +static u8 sdhci_am654_write_power_on(struct sdhci_host *host, u8 val, int reg) +{ + writeb(val, host->ioaddr + reg); + usleep_range(1000, 10000); + return readb(host->ioaddr + reg); +} + +#define MAX_POWER_ON_TIMEOUT 1500000 /* us */ static void sdhci_am654_write_b(struct sdhci_host *host, u8 val, int reg) { unsigned char timing = host->mmc->ios.timing; + u8 pwr; + int ret; if (reg == SDHCI_HOST_CONTROL) { switch (timing) { @@ -291,6 +302,19 @@ static void sdhci_am654_write_b(struct sdhci_host *host, u8 val, int reg) } writeb(val, host->ioaddr + reg); + if (reg == SDHCI_POWER_CONTROL && (val & SDHCI_POWER_ON)) { + /* + * Power on will not happen until the card detect debounce + * timer expires. Wait at least 1.5 seconds for the power on + * bit to be set + */ + ret = read_poll_timeout(sdhci_am654_write_power_on, pwr, + pwr & SDHCI_POWER_ON, 0, + MAX_POWER_ON_TIMEOUT, false, host, val, + reg); + if (ret) + dev_warn(mmc_dev(host->mmc), "Power on failed\n"); + } } static int sdhci_am654_execute_tuning(struct mmc_host *mmc, u32 opcode) |