linux-kernel - Re: [PATCH v2 06/11] mmc: sdhci: xenon: Use sdhci_set_power_and

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Message-ID: <d75a2a63-a657-6584-5ce2-c2e5550ccf39@intel.com>
Date:   Mon, 9 Mar 2020 13:56:58 +0200
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Nicolas Saenz Julienne <nsaenzjulienne@...e.de>,
        linux-kernel@...r.kernel.org, Hu Ziji <huziji@...vell.com>,
        Zhoujie Wu <zjwu@...vell.com>
Cc:     phil@...pberrypi.com, linux-mmc@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, f.fainelli@...il.com,
        stefan.wahren@...e.com, bcm-kernel-feedback-list@...adcom.com,
        linux-rpi-kernel@...ts.infradead.org,
        Ulf Hansson <ulf.hansson@...aro.org>
Subject: Re: [PATCH v2 06/11] mmc: sdhci: xenon: Use
 sdhci_set_power_and_voltage()

+ Zhoujie Wu <zjwu@...vell.com>

On 9/03/20 1:55 pm, Adrian Hunter wrote:
> On 9/03/20 12:53 pm, Nicolas Saenz Julienne wrote:
>> On Mon, 2020-03-09 at 09:20 +0200, Adrian Hunter wrote:
>>>> -static void xenon_set_power(struct sdhci_host *host, unsigned char mode,
>>>> -		unsigned short vdd)
>>>> -{
>>>> -	struct mmc_host *mmc = host->mmc;
>>>> -	u8 pwr = host->pwr;
>>>> -
>>>> -	sdhci_set_power_noreg(host, mode, vdd);
>>>> -
>>>> -	if (host->pwr == pwr)
>>>> -		return;
>>>> -
>>>> -	if (host->pwr == 0)
>>>> -		vdd = 0;
>>>> -
>>>> -	if (!IS_ERR(mmc->supply.vmmc))
>>>> -		mmc_regulator_set_ocr(mmc, mmc->supply.vmmc, vdd);
>>>> -}
>>>
>>> This code is different.  The commit message should explain why it is
>>> equivalent.  Has it been tested?
>>
>> Yes, I should've pointed it out. The rationale behind including sdhci-xenon and
>> sdhci-pxav3 is based on xenon's original commit message (99c14fc360dbb):
>>
>> 	mmc: sdhci-xenon: add set_power callback
>>
>> 	Xenon sdh controller requests proper SD bus voltage select
>> 	bits programmed even with vmmc power supply. Any reserved
>> 	value(100b-000b) programmed in this field will lead to controller
>> 	ignore SD bus power bit and keep its value at zero.
>> 	Add set_power callback to handle this.
>>
>> I can't test it, but it felt to me as the implementation differences are only
>> there as different people wrote the code. Ultimately, I'll be happy to drop
>> them from the series if you feel it's too much of an assumption, I can see how
>> the controllers could react badly to the ordering change. If not I can send a
>> v3 with fixed commit messages.
> 
> We can wait a bit and see if anyone provides a Tested-by tag, otherwise
> safer to drop it.
>