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 <[email protected]>
---
drivers/mmc/host/sdhci_am654.c | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)
diff --git a/drivers/mmc/host/sdhci_am654.c b/drivers/mmc/host/sdhci_am654.c
index 1718b9e8af63..55cff9de2f3e 100644
--- a/drivers/mmc/host/sdhci_am654.c
+++ b/drivers/mmc/host/sdhci_am654.c
@@ -272,6 +272,7 @@ static void sdhci_j721e_4bit_set_clock(struct sdhci_host *host,
sdhci_set_clock(host, clock);
}
+#define MAX_POWER_ON_TIMEOUT 1500 /* ms */
static void sdhci_am654_write_b(struct sdhci_host *host, u8 val, int reg)
{
unsigned char timing = host->mmc->ios.timing;
@@ -291,6 +292,26 @@ 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
+ */
+ ktime_t timeout = ktime_add_ms(ktime_get(),
+ MAX_POWER_ON_TIMEOUT);
+ do {
+ if (ktime_compare(ktime_get(), timeout) > 0) {
+ dev_warn(mmc_dev(host->mmc),
+ "Power on failed\n");
+
+ return;
+ }
+
+ writeb(val, host->ioaddr + reg);
+ usleep_range(1000, 10000);
+ } while (!(readb(host->ioaddr + reg) & SDHCI_POWER_ON));
+ }
}
static int sdhci_am654_execute_tuning(struct mmc_host *mmc, u32 opcode)
--
2.17.1
On 30/07/20 2:41 am, Faiz Abbas 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 <[email protected]>
> ---
> drivers/mmc/host/sdhci_am654.c | 21 +++++++++++++++++++++
> 1 file changed, 21 insertions(+)
>
> diff --git a/drivers/mmc/host/sdhci_am654.c b/drivers/mmc/host/sdhci_am654.c
> index 1718b9e8af63..55cff9de2f3e 100644
> --- a/drivers/mmc/host/sdhci_am654.c
> +++ b/drivers/mmc/host/sdhci_am654.c
> @@ -272,6 +272,7 @@ static void sdhci_j721e_4bit_set_clock(struct sdhci_host *host,
> sdhci_set_clock(host, clock);
> }
>
> +#define MAX_POWER_ON_TIMEOUT 1500 /* ms */
> static void sdhci_am654_write_b(struct sdhci_host *host, u8 val, int reg)
> {
> unsigned char timing = host->mmc->ios.timing;
> @@ -291,6 +292,26 @@ 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
> + */
Can you use readb_poll_timeout() here?
> + ktime_t timeout = ktime_add_ms(ktime_get(),
> + MAX_POWER_ON_TIMEOUT);
> + do {
> + if (ktime_compare(ktime_get(), timeout) > 0) {
> + dev_warn(mmc_dev(host->mmc),
> + "Power on failed\n");
> +
> + return;
> + }
> +
> + writeb(val, host->ioaddr + reg);
> + usleep_range(1000, 10000);
> + } while (!(readb(host->ioaddr + reg) & SDHCI_POWER_ON));
> + }
> }
>
> static int sdhci_am654_execute_tuning(struct mmc_host *mmc, u32 opcode)
>
Hi Adrian,
On 05/08/20 1:44 pm, Adrian Hunter wrote:
> On 30/07/20 2:41 am, Faiz Abbas 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 <[email protected]>
>> ---
>> drivers/mmc/host/sdhci_am654.c | 21 +++++++++++++++++++++
>> 1 file changed, 21 insertions(+)
>>
>> diff --git a/drivers/mmc/host/sdhci_am654.c b/drivers/mmc/host/sdhci_am654.c
>> index 1718b9e8af63..55cff9de2f3e 100644
>> --- a/drivers/mmc/host/sdhci_am654.c
>> +++ b/drivers/mmc/host/sdhci_am654.c
>> @@ -272,6 +272,7 @@ static void sdhci_j721e_4bit_set_clock(struct sdhci_host *host,
>> sdhci_set_clock(host, clock);
>> }
>>
>> +#define MAX_POWER_ON_TIMEOUT 1500 /* ms */
>> static void sdhci_am654_write_b(struct sdhci_host *host, u8 val, int reg)
>> {
>> unsigned char timing = host->mmc->ios.timing;
>> @@ -291,6 +292,26 @@ 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
>> + */
>
> Can you use readb_poll_timeout() here?
>
The loop is write -> readback -> check for set bit -> write again and so on until timeout
so poll_timeout() calls will not work.
Thanks,
Faiz
On 5/08/20 11:22 am, Faiz Abbas wrote:
> Hi Adrian,
>
> On 05/08/20 1:44 pm, Adrian Hunter wrote:
>> On 30/07/20 2:41 am, Faiz Abbas 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 <[email protected]>
>>> ---
>>> drivers/mmc/host/sdhci_am654.c | 21 +++++++++++++++++++++
>>> 1 file changed, 21 insertions(+)
>>>
>>> diff --git a/drivers/mmc/host/sdhci_am654.c b/drivers/mmc/host/sdhci_am654.c
>>> index 1718b9e8af63..55cff9de2f3e 100644
>>> --- a/drivers/mmc/host/sdhci_am654.c
>>> +++ b/drivers/mmc/host/sdhci_am654.c
>>> @@ -272,6 +272,7 @@ static void sdhci_j721e_4bit_set_clock(struct sdhci_host *host,
>>> sdhci_set_clock(host, clock);
>>> }
>>>
>>> +#define MAX_POWER_ON_TIMEOUT 1500 /* ms */
>>> static void sdhci_am654_write_b(struct sdhci_host *host, u8 val, int reg)
>>> {
>>> unsigned char timing = host->mmc->ios.timing;
>>> @@ -291,6 +292,26 @@ 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
>>> + */
>>
>> Can you use readb_poll_timeout() here?
>>
>
> The loop is write -> readback -> check for set bit -> write again and so on until timeout
> so poll_timeout() calls will not work.
I mentioned it because pedantically you need to check the condition
again after a timeout. Alternatively, the read_poll_timeout macro
can be used with a function, something like below (not even compile
tested!)
static u8 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;
if (reg == SDHCI_HOST_CONTROL) {
switch (timing) {
/*
* According to the data manual, HISPD bit
* should not be set in these speed modes.
*/
case MMC_TIMING_SD_HS:
case MMC_TIMING_MMC_HS:
case MMC_TIMING_UHS_SDR12:
case MMC_TIMING_UHS_SDR25:
val &= ~SDHCI_CTRL_HISPD;
}
}
writeb(val, host->ioaddr + reg);
/*
* 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
*/
if (reg == SDHCI_POWER_CONTROL && (val & SDHCI_POWER_ON) &&
read_poll_timeout(write_power_on, pwr, (pwr & SDHCI_POWER_ON), 0,
MAX_POWER_ON_TIMEOUT, false, host, val, reg))
dev_warn(mmc_dev(host->mmc), "Power on failed\n");
return;
}
}
}