On Wed, Dec 11, 2013 at 9:56 AM, Shawn Guo <shawn.guo@xxxxxxxxxx> wrote:
> On Tue, Dec 10, 2013 at 08:56:03PM +0800, Dong Aisheng wrote:
>> Currently the max_discard_to is simply got by (1 << 27) / host->timeout_clk
>> which is assumed to be the maximum timeout value, however, some platforms
>> maximum timeout counter may not be 1 << 27, e.g. i.MX uSDHC is 1 << 28.
>> Thus 1 << 27 may not be correct for such platforms.
>>
>> It is also possible that other platforms may have different problems.
>> To be flexible, we add a get_max_timeout hook to get the correct
>> maximum timeout value for these platforms.
>>
>> Signed-off-by: Dong Aisheng <b29396@xxxxxxxxxxxxx>
>> Reported-by: Ed Sutter <ed.sutter@xxxxxxxxxxxxxxxxxx>
>> ---
>> drivers/mmc/host/sdhci.c | 5 ++++-
>> drivers/mmc/host/sdhci.h | 1 +
>> 2 files changed, 5 insertions(+), 1 deletions(-)
>>
>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
>> index bd8a098..464d42c 100644
>> --- a/drivers/mmc/host/sdhci.c
>> +++ b/drivers/mmc/host/sdhci.c
>> @@ -2930,7 +2930,10 @@ int sdhci_add_host(struct sdhci_host *host)
>> if (host->quirks & SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK)
>> host->timeout_clk = mmc->f_max / 1000;
>>
>> - mmc->max_discard_to = (1 << 27) / host->timeout_clk;
>> + if (host->ops->get_max_timeout)
>> + mmc->max_discard_to = host->ops->get_max_timeout(host);
>
> Does "timeout" conceptually equals to "discard_to"? If not, we might
> want to write it in the either form below to avoid messing these two
> concepts.
>
No, they're two concepts but the max_discard_to equals to the max timeout value
the host supports.
> mmc->max_discard_to = host->ops->get_max_timeout(host) / host->timeout_clk;
>
> or
>
> mmc->max_discard_to = host->ops->get_max_discard_to(host);
>
> I guess you may want to go for the second one.
>
The original way looks ok to me.
Platform host driver does not need to know detail about discard,
just tell the max timeout value it supports is ok.
Common sdhci driver will handle it well.
Regards
Dong Aisheng
> Shawn
>
>> + else
>> + mmc->max_discard_to = (1 << 27) / host->timeout_clk;
>>
>> mmc->caps |= MMC_CAP_SDIO_IRQ | MMC_CAP_ERASE | MMC_CAP_CMD23;
>>
>> diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
>> index 0a3ed01..1591cbb 100644
>> --- a/drivers/mmc/host/sdhci.h
>> +++ b/drivers/mmc/host/sdhci.h
>> @@ -281,6 +281,7 @@ struct sdhci_ops {
>> unsigned int (*get_max_clock)(struct sdhci_host *host);
>> unsigned int (*get_min_clock)(struct sdhci_host *host);
>> unsigned int (*get_timeout_clock)(struct sdhci_host *host);
>> + unsigned int (*get_max_timeout)(struct sdhci_host *host);
>> int (*platform_bus_width)(struct sdhci_host *host,
>> int width);
>> void (*platform_send_init_74_clocks)(struct sdhci_host *host,
>> --
>> 1.7.2.rc3
>>
>>
>
>
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