| Message ID | 20200825170015.32285-1-faiz_abbas@ti.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] mmc: sdhci_am654: Add workaround for card detect debounce timer | expand |
On Tue, 25 Aug 2020 at 19:00, Faiz Abbas <faiz_abbas@ti.com> wrote: > > 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> Applied for next, thanks! Kind regards Uffe > --- > > v2: Use read_poll_timeout() standard macro > > drivers/mmc/host/sdhci_am654.c | 24 ++++++++++++++++++++++++ > 1 file changed, 24 insertions(+) > > diff --git a/drivers/mmc/host/sdhci_am654.c b/drivers/mmc/host/sdhci_am654.c > index f9d24af12396..9a048c80dad4 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) > -- > 2.17.1 >
diff --git a/drivers/mmc/host/sdhci_am654.c b/drivers/mmc/host/sdhci_am654.c index f9d24af12396..9a048c80dad4 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)
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> --- v2: Use read_poll_timeout() standard macro drivers/mmc/host/sdhci_am654.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+)