linux-kernel - Re: [PATCH 4/4] mmc: dw_mmc: exynos: use common

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Message-ID: <YaDVZ94vQ/O5djuA@donbot>
Date:   Fri, 26 Nov 2021 12:39:03 +0000
From:   John Keeping <john@...anate.com>
To:     Jaehoon Chung <jh80.chung@...sung.com>
Cc:     linux-mmc@...r.kernel.org, Heiko Stuebner <heiko@...ech.de>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-rockchip@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org,
        Ulf Hansson <ulf.hansson@...aro.org>
Subject: Re: [PATCH 4/4] mmc: dw_mmc: exynos: use common_caps

On Fri, Nov 26, 2021 at 08:38:20AM +0900, Jaehoon Chung wrote:
> On 11/25/21 3:46 AM, John Keeping wrote:
> > Move the common MMC_CAP_CMD23 capability to common_caps so that only the
> > special case of MMC_CAP_1_8V_DDR and MMC_CAP_8_BIT_DATA are set via
> > caps/num_caps.  Both of those can, and should, be set via device tree
> > properties instead, so we can now say that exynos_dwmmc_caps is only
> > used for backwards compatibility.
> > 
> > Signed-off-by: John Keeping <john@...anate.com>
> 
> 
> Reviewed-by: Jaehoon Chung <jh80.chung@...sung.com>
> 
> Added minor comment..
> 
> > ---
> >  drivers/mmc/host/dw_mmc-exynos.c | 9 +++++----
> >  1 file changed, 5 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/mmc/host/dw_mmc-exynos.c b/drivers/mmc/host/dw_mmc-exynos.c
> > index c2dd29ef45c6..f76eeeb0cc53 100644
> > --- a/drivers/mmc/host/dw_mmc-exynos.c
> > +++ b/drivers/mmc/host/dw_mmc-exynos.c
> > @@ -526,15 +526,16 @@ static int dw_mci_exynos_prepare_hs400_tuning(struct dw_mci *host,
> >  
> >  /* Common capabilities of Exynos4/Exynos5 SoC */
> >  static unsigned long exynos_dwmmc_caps[4] = {
> > -	MMC_CAP_1_8V_DDR | MMC_CAP_8_BIT_DATA | MMC_CAP_CMD23,
> > -	MMC_CAP_CMD23,
> > -	MMC_CAP_CMD23,
> > -	MMC_CAP_CMD23,
> > +	MMC_CAP_1_8V_DDR | MMC_CAP_8_BIT_DATA,
> > +	0,
> > +	0,
> > +	0,
> >  };
> 
> It can be removed all things.

Do you mean that the MMC_CAP_1_8V_DDR | MMC_CAP_8_BIT_DATA entries are
not needed at all?

I know those can be set via DT but I don't think any Exynos DTs are
currently using mmc-ddr-1_8v, so removing MMC_CAP_1_8V_DDR looks like a
change in behaviour.

MMC_CAP_8_BIT_DATA looks easier to remove, although
exynos4412-p4note.dtsi seems to set the incorrect bus-width for mshc_0
so there would be a change of behaviour on that platform from removing
this.

Maybe it makes sense to add a warning in dw_mci_init_slot_caps() if any
new caps are set by drv_data->caps[ctrl_id], to make it clear that this
is deprecated.


Regards,
John