linux-kernel - Re: [PATCH 2/3] mmc: dw_mmc: simplify the SDMMC_CLKEN_LOW

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Message-ID: <CAGOxZ53FipjSbYMeBfr_+OWxn_WxpDfbfr8Vzs4uX6t3TBS3vw@mail.gmail.com>
Date:	Mon, 17 Aug 2015 21:51:26 +0530
From:	Alim Akhtar <alim.akhtar@...il.com>
To:	Michal Suchanek <hramrach@...il.com>
Cc:	Jaehoon Chung <jh80.chung@...sung.com>,
	linux-sunxi <linux-sunxi@...glegroups.com>,
	Seungwon Jeon <tgih.jun@...sung.com>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	David Lanzendörfer <david.lanzendoerfer@....ch>,
	Hans de Goede <hdegoede@...hat.com>,
	Chen-Yu Tsai <wens@...e.org>, Arnd Bergmann <arnd@...db.de>,
	linux-mmc <linux-mmc@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 2/3] mmc: dw_mmc: simplify the SDMMC_CLKEN_LOW_PWR logic

Hi Michal,

On Mon, Aug 17, 2015 at 8:25 PM, Michal Suchanek <hramrach@...il.com> wrote:
>  Hello,
>
> On 17 August 2015 at 16:42, Alim Akhtar <alim.akhtar@...il.com> wrote:
>> HI
>>
>> On Mon, Aug 17, 2015 at 4:56 PM, Jaehoon Chung <jh80.chung@...sung.com> wrote:
>>> On 08/17/2015 02:52 PM, Michal Suchanek wrote:
>>>> Hello,
>>>>
>>>> On 17 August 2015 at 03:55, Jaehoon Chung <jh80.chung@...sung.com> wrote:
>>>>> Hi, Michal.
>>>>>
>>>>> On 08/12/2015 09:23 PM, Michal Suchanek wrote:
>>>>>> The driver has open-coded test for SDIO cards. Use the mmc core provided
>>>>>> MMC_QUIRK_BROKEN_CLK_GATING flag instead.
>>>>>
>>>>> Did you use the clock-gating for SDIO cards?
>>>>> Doesn't MMC_CAP_SDIO_IRQ bit set? Which case is broken?
>>>>> Could you explain to me more?
>>>>
>>>> The core flag for disabling power saving is MMC_QUIRK_BROKEN_CLK_GATING.
>>>
>>> I understood your intention. And i read the comment into mmc/core/quirks.c
>>> I will test SDIO card with this patch. Thanks.
>>>
>> When you test, please check if SDIO IRQ still works, we need to put
>> dw_mmc in low_power mode otherwise SDIO IRQ will be not be generated
>> by dw_mmc host controller.
>>
>
> As far as I understand the logic which is removed in this patch and
> the core logic which replaces it is the same -  low power by means of
> clock gating is *not* enabled for SDIO cards in either case.
>
> The original code also checks for SDIO IRQ and disables clock gating
> regardless of card type which is probably redundant. If not it should
> be fixed in mmc core.
>
> My recent kernel builds which I run on a system with mwifiex card
> probably include this patch.
>
I have no objection to this patch as such, it just that some extra
testing on few other boards will be good, which I am sure Jeahoon will
take care.
Thanks!!

> Thanks
>
> Michal



-- 
Regards,
Alim
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