Re: [PATCH] qcom: sdhci-msm: enable the DLL clock

From	Ulf Hansson <ulf.hansson@linaro.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH] qcom: sdhci-msm: enable the DLL clock
Date	2016-04-13 13:50 +0200
Message-ID	<rnrt0-BH-23@gated-at.bofh.it> (permalink)
References	<rktUm-8dF-33@gated-at.bofh.it> <rmKem-6GA-41@gated-at.bofh.it> <rmSlA-4EU-11@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On 12 April 2016 at 00:11, Stephen Boyd <sboyd@codeaurora.org> wrote:
> On 04/11, Ulf Hansson wrote:
>> + Adrian
>>
>> On 5 April 2016 at 09:46, Sreedhar Sambangi <ssambang@codeaurora.org> wrote:
>> > The DLL clock has to be enabled until the correct
>> > clock frequency is delivered to DLL
>> > '1'(default) - DLL clock is disabled
>> > '0' - dll clock has legacly clock enable.
>> >
>> > Signed-off-by: Varadarajan Narayanan <varada@codeaurora.org>
>> > Signed-off-by: Sreedhar Sambangi <ssambang@codeaurora.org>
>>
>> Adrian Hunter is the maintainer for sdhci, next time make sure to post to him.
>>
>> As this seems like fairly trivial change I decided to pick it up
>> anyway. So applied for next!
>>
>> Note, that I changed the prefix of the commit message header to "mmc".
>>
>
> I'm not sure this patch is actually right. In the downstream
> sources we do quite a few more reads and writes if we need to
> poke this second DLL configuration register. Furthermore, on
> msm8974 and apq8084 this register doesn't even exist so writing
> to it may cause problems if it isn't write ignored (I haven't
> checked).
>
> I think we should follow the downstream kernel design instead.
> Namely, reading the major/minor version registers to figure out
> if we should be touching this register in the first place, and
> then adding a clock property to the DT binding for the XO source
> so we can determine the XO frequency. It seems that we need this
> frequency to figure out how to program the second DLL
> configuration register appropriately.

Stephen,

Thanks for reviewing. I have dropped this patch for now.

Kind regards
Uffe

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[PATCH] qcom: sdhci-msm: enable the DLL clock Sreedhar Sambangi <ssambang@codeaurora.org> - 2016-04-05 09:50 +0200
  Re: [PATCH] qcom: sdhci-msm: enable the DLL clock Ulf Hansson <ulf.hansson@linaro.org> - 2016-04-11 15:40 +0200
    Re: [PATCH] qcom: sdhci-msm: enable the DLL clock Stephen Boyd <sboyd@codeaurora.org> - 2016-04-12 00:20 +0200
      Re: [PATCH] qcom: sdhci-msm: enable the DLL clock Ulf Hansson <ulf.hansson@linaro.org> - 2016-04-13 13:50 +0200

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