linux-kernel - Re: [PATCH 1/2] arm64: dts: exynos: drop mshc aliases

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Date:   Sat, 4 Feb 2023 17:27:15 +0100
From:   Henrik Grimler <henrik@...mler.se>
To:     David Virag <virag.david003@...il.com>
Cc:     robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        alim.akhtar@...sung.com, m.szyprowski@...sung.com,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
        phone-devel@...r.kernel.org, ~postmarketos/upstreaming@...ts.sr.ht
Subject: Re: [PATCH 1/2] arm64: dts: exynos: drop mshc aliases

Hi David,

On Sat, Feb 04, 2023 at 01:45:15PM +0100, David Virag wrote:
> On Sat, 2023-02-04 at 12:43 +0100, David Virag wrote:
> > On Fri, 2023-02-03 at 21:39 +0100, Henrik Grimler wrote:
> > > They are no longer needed after commit a13e8ef6008d ("mmc: dw_mmc:
> > > exynos: use common_caps").
> > > 
> > > Signed-off-by: Henrik Grimler <henrik@...mler.se>
> > > ---
> > >  arch/arm64/boot/dts/exynos/exynos5433-tm2-common.dtsi | 2 --
> > >  arch/arm64/boot/dts/exynos/exynos7-espresso.dts       | 2 --
> > >  2 files changed, 4 deletions(-)
> [...]
> > In dw_mmc-exynos.c, there's a caps array specified like this:
> > 
> > /* Common capabilities of Exynos4/Exynos5 SoC */
> > static unsigned long exynos_dwmmc_caps[4] = {
> >         MMC_CAP_1_8V_DDR | MMC_CAP_8_BIT_DATA,
> >         0,
> >         0,
> >         0,
> > };
> > 
> > As I understand these capabilities are added to the mmc controllers
> > based on mshc alias id. Shouldn't these capabilities be moved to
> > device-tree before removing these aliases? This also applies to the
> > 32bit arm patch. If I understand correctly, removing these aliases
> > without adding the capabilities to dt removes the capability
> > "MMC_CAP_1_8V_DDR" and "MMC_CAP_8_BIT_DATA" from mshc_0/mmc_0.

Thanks for pointing this out (I should have seen it already), will
send a new version to update device trees and remove the need for
those mshc alias based capabilities.

> Actually, it defaults to 0, so these capabilities will be added to all
> mmc nodes, not just those with mshc0 alias. That may cause problems.

I think I see what you mean: ctrl_id will be set to 0 if mshc alias is
missing, and then caps is set as
    mmc->caps |= drv_data->caps[ctrl_id];
where
    drv_data->caps[0] = MMC_CAP_1_8V_DDR | MMC_CAP_8_BIT_DATA

Should be fixed in next version of patchset then in any case, maybe it
deserves a "Fixes:" tag as well, will have a look in git history if
there is a particular commit that introduced this situation.

> Best regards,
> David

Best regards,
Henrik Grimler