linux-kernel - Re: [PATCH] drm/ssd130x: Use new regmap bulk write support to drop custom bus

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Message-ID: <51214426-a893-cac3-b984-97688838c896@redhat.com>
Date:   Mon, 18 Jul 2022 11:13:32 +0200
From:   Javier Martinez Canillas <javierm@...hat.com>
To:     Sam Ravnborg <sam@...nborg.org>
Cc:     Marek Vasut <marex@...x.de>, David Airlie <airlied@...ux.ie>,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Thomas Zimmermann <tzimmermann@...e.de>
Subject: Re: [PATCH] drm/ssd130x: Use new regmap bulk write support to drop
 custom bus

Hello Sam,

On 6/24/22 21:37, Sam Ravnborg wrote:
> Hi Javier,
> 
> On Sat, Jun 18, 2022 at 07:43:38PM +0200, Javier Martinez Canillas wrote:
>> Data writes for the ssd130x 4-wire SPI protocol need special handling, due
>> the Data/Command control (D/C) pin having to be toggled prior to the write.
>>
>> The regmap API only allowed drivers to provide .reg_{read,write} callbacks
>> to do per register read/write, but didn't provide a way for drivers to do
>> the same for bulk read/writes.
>>
>> For this reason, a custom regmap bus was used by the driver just to define
>> a bulk write callback that implements the D/C pin toggling. But the regmap
>> API has been extended to support defining bulk read/write handlers, so the
>> custom regmap bus is not needed anymore and could just be dropped.
>>
>> Signed-off-by: Javier Martinez Canillas <javierm@...hat.com>
> Patch looks good, but obviously needs the dependencies sorted out.
> Acked-by: Sam Ravnborg <sam@...nborg.org>
>

Thanks. The regmap fixes that were the dependencies landed in v5.19-rc4
and drm-misc-next is already at v5.19-rc6, so I'll push this patch now.

-- 
Best regards,

Javier Martinez Canillas
Linux Engineering
Red Hat