linux-kernel - Re: [PATCH v1 09/11] mmc: mmci: Add clock support for Qualcomm.

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Date:	Tue, 13 May 2014 10:39:14 +0100
From:	Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To:	Linus Walleij <linus.walleij@...aro.org>
CC:	Russell King <linux@....linux.org.uk>,
	"linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
	Chris Ball <chris@...ntf.net>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	agross@...cinc.com,
	"linux-arm-msm@...r.kernel.org" <linux-arm-msm@...r.kernel.org>
Subject: Re: [PATCH v1 09/11] mmc: mmci: Add clock support for Qualcomm.

Thanks Linus W,

On 13/05/14 09:28, Linus Walleij wrote:
>> code is conditioned on hw designer.
>>
>> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
> (...)
>> +               if (host->hw_designer == AMBA_VENDOR_QCOM) {
>> +                       host->cclk = host->mclk;
>> +               } else if (desired >= host->mclk) {
>
> Again refrain from hard-checking the vendor everywhere.
>
> struct variant_data {
>          bool            qcom_cclk_is_mclk;
> (...)
>
Got it.. Will fix it in next version.
> As per example from st_clkdiv...
>
> Then
>
> if (host->vendor->qcom_cclk_is_mclk) {
>    (...)
> }
>
>> +       if (ios->clock != host->mclk &&
>> +               host->hw_designer == AMBA_VENDOR_QCOM) {
>> +               /* Qcom MCLKCLK register does not define bypass bits */
>> +               int rc = clk_set_rate(host->clk, ios->clock);
>> +               if (rc < 0) {
>> +                       dev_err(mmc_dev(host->mmc),
>> +                               "Error setting clock rate (%d)\n", rc);
>> +               } else {
>> +                       host->mclk = clk_get_rate(host->clk);
>> +                       host->cclk = host->mclk;
>> +               }
>> +       }
>
> For this I would define a vendor data like:
>
> struct variant_data {
>          bool            explicit_mclk_control;
> (...)
This looks good.
>
> Or something. It explains what is actually going on.
>
>>          if (plat->f_max)
>> -               mmc->f_max = min(host->mclk, plat->f_max);
>> +               mmc->f_max = (host->hw_designer == AMBA_VENDOR_QCOM) ?
>> +                               plat->f_max : min(host->mclk, plat->f_max);
>
> So rewrite like that:
>
> if (host->vendor->explicit_mclk_control)
>         mmc->f_max = plat->f_max;
> else
>        mmc->f_max = min(host->mclk, plat->f_max);
>

This looks much clean


> Yours,
> Linus Walleij
>
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