linux-kernel - Re: [PATCH 1/3] mmc: fix mmc mode selection for HS-DDR and higher

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Date:	Wed, 1 Jun 2016 11:58:34 -0700
From:	Bjorn Andersson <bjorn.andersson@...aro.org>
To:	Chen-Yu Tsai <wens@...e.org>
Cc:	Ulf Hansson <ulf.hansson@...aro.org>,
	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	Hans de Goede <hdegoede@...hat.com>,
	linux-mmc <linux-mmc@...r.kernel.org>,
	linux-arm-kernel@...ts.infradead.org,
	lkml <linux-kernel@...r.kernel.org>,
	Arnd Bergmann <arnd@...db.de>
Subject: Re: [PATCH 1/3] mmc: fix mmc mode selection for HS-DDR and higher

On Sun, May 29, 2016 at 12:04 AM, Chen-Yu Tsai <wens@...e.org> wrote:
> When IS_ERR_VALUE was removed from the mmc core code, it was replaced
> with a simple not-zero check. This does not work, as the value checked
> is the return value for mmc_select_bus_width, which returns the set
> bit width on success. This made eMMC modes higher than HS-DDR unusable.
>
> Fix this by checking for a positive return value instead.

mmc_select_bus_width() can return 0 on "success" as well and the
previous check was !IS_ERR_VALUE(err), which coverts that. So I
believe these checks should be for err >= 0 rather than just > 0.


Either way this fixes the boot failures seen on my Qualcomm based
boards with v4.7-rc1.

Regards,
Bjorn