On 11/27/2018 04:43 AM, Masahiro Yamada wrote:
> On Wed, Nov 14, 2018 at 8:44 AM Marek Vasut <marek.va...@gmail.com> wrote:
>>
>> The TMIO core has a feature where it can automatically disable clock output
>> when the bus is not in use. While this is useful, it also interferes with
>> switching the bus to 1.8V and other background tasks of the SD/MMC cards,
>> which require clock to be enabled.
>>
>> This patch respects the mmc->clk_disable and only disables the clock when
>> the MMC core requests it. Otherwise the clock are continuously generated
>> on the bus.
>>
>> Signed-off-by: Marek Vasut <marek.vasut+rene...@gmail.com>
>> Cc: Masahiro Yamada <yamada.masah...@socionext.com>
>> ---
>> drivers/mmc/tmio-common.c | 10 ++++++++--
>> 1 file changed, 8 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/mmc/tmio-common.c b/drivers/mmc/tmio-common.c
>> index 424b60ce52..fad2816ca5 100644
>> --- a/drivers/mmc/tmio-common.c
>> +++ b/drivers/mmc/tmio-common.c
>> @@ -612,10 +612,16 @@ static void tmio_sd_set_clk_rate(struct tmio_sd_priv
>> *priv,
>> tmio_sd_writel(priv, tmp, TMIO_SD_CLKCTL);
>>
>> tmp &= ~TMIO_SD_CLKCTL_DIV_MASK;
>> - tmp |= val | TMIO_SD_CLKCTL_OFFEN;
>> + tmp |= val;
>> tmio_sd_writel(priv, tmp, TMIO_SD_CLKCTL);
>>
>> - tmp |= TMIO_SD_CLKCTL_SCLKEN;
>> + if (!mmc->clk_disable) {
>> + tmp &= ~TMIO_SD_CLKCTL_OFFEN;
>> + tmp |= TMIO_SD_CLKCTL_SCLKEN;
>> + } else {
>> + tmp |= TMIO_SD_CLKCTL_OFFEN;
>> + tmp &= ~TMIO_SD_CLKCTL_SCLKEN;
>> + }
>> tmio_sd_writel(priv, tmp, TMIO_SD_CLKCTL);
>>
>> udelay(1000);
>
>
>
> What is the point of setting TMIO_SD_CLKCTL_OFFEN
> when TMIO_SD_CLKCTL_SCLKEN is unset?
>
>
> Why isn't the code like this?
>
>
> if (!mmc->clk_disable)
> tmp |= TMIO_SD_CLKCTL_SCLKEN;
> else
> tmp &= ~TMIO_SD_CLKCTL_SCLKEN;
>
> /* Never use OFFEN because it interferes with 1.8 switching */
> tmp &= ~TMIO_SD_CLKCTL_OFFEN;
>
> tmio_sd_writel(priv, tmp, TMIO_SD_CLKCTL);
>
I think this could be done, but I'd have to re-run the entire bulk of
tests on all boards to see if nothing broke. I'd prefer to get this in
(if it doesn't break your system) and then add a patch on top.
> One more thing, you wrote
>
> if (!mmc->clk_disable)
> ...
> else
> ...
>
> in this patch.
>
>
> Then, soon you will rewrite it to
>
> if (mmc->clk_disable)
> ...
> else
> ...
>
> in another patch:
>
> http://patchwork.ozlabs.org/patch/998542/
I know, I added the other one afterward, since I discovered another card
which had clock problems.
--
Best regards,
Marek Vasut
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