Re: [PATCH] mmc: renesas_sdhi: Fix card initialization failure in high speed mode

From: Marek Vasut <marek.vasut@gmail.com>
To: Ulf Hansson <ulf.hansson@linaro.org>
Cc: "linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>,
	"Takeshi Saito" <takeshi.saito.xv@renesas.com>,
	"Marek Vasut" <marek.vasut+renesas@gmail.com>,
	"Niklas Söderlund" <niklas.soderlund+renesas@ragnatech.se>,
	"Simon Horman" <horms+renesas@verge.net.au>,
	"Wolfram Sang" <wsa+renesas@sang-engineering.com>,
	Linux-Renesas <linux-renesas-soc@vger.kernel.org>
Subject: Re: [PATCH] mmc: renesas_sdhi: Fix card initialization failure in high speed mode
Date: Tue, 29 Jan 2019 10:56:23 +0100	[thread overview]
Message-ID: <c0ae0fd2-3dbb-0e65-529e-99b78e0624f5@gmail.com> (raw)
In-Reply-To: <CAPDyKFpa=q+oSES115SBUnpFVq+nUGwH7sY5F=go4-rZp6EasQ@mail.gmail.com>

On 1/29/19 9:05 AM, Ulf Hansson wrote:
> On Tue, 29 Jan 2019 at 06:40, <marek.vasut@gmail.com> wrote:
>>
>> From: Takeshi Saito <takeshi.saito.xv@renesas.com>
>>
>> This fixes card initialization failure in high speed mode.
>>
>> If U-Boot uses SDR or HS200/400 mode before starting Linux and Linux
>> DT does not enable SDR/HS200/HS400 mode, card initialization fails in
>> high speed mode.
>>
>> It is necessary to initialize SCC registers during card initialization
>> phase. HW reset function is registered only for a port with either of
>> SDR/HS200/HS400 properties in device tree. If SDR/HS200/HS400 properties
>> are not present in device tree, SCC registers will not be reset. In SoC
>> that support SCC registers, HW reset function should be registered
>> regardless of the configuration of device tree.
>>
>> Reproduction procedure:
>> - Use U-Boot that support MMC HS200/400 mode.
>> - Delete HS200/HS400 properties in device tree.
>>   (Delete mmc-hs200-1_8v and mmc-hs400-1_8v)
>> - MMC port works high speed mode and all commands fail.
>>
>> Signed-off-by: Takeshi Saito <takeshi.saito.xv@renesas.com>
>> Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
>> Cc: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
>> Cc: Simon Horman <horms+renesas@verge.net.au>
>> Cc: Ulf Hansson <ulf.hansson@linaro.org>
>> Cc: Wolfram Sang <wsa+renesas@sang-engineering.com>
>> Cc: linux-renesas-soc@vger.kernel.org
>> To: linux-mmc@vger.kernel.org
> 
> Is this a regression?

No, because this was broken since the beginning. But U-Boot HS200/HS400
support is now, so this bug was hidden.

> Should it be tagged for stable?

I am tempted to say yes.

-- 
Best regards,
Marek Vasut