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

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Date:   Fri, 24 Jun 2022 21:37:27 +0200
From:   Sam Ravnborg <sam@...nborg.org>
To:     Javier Martinez Canillas <javierm@...hat.com>
Cc:     linux-kernel@...r.kernel.org, Marek Vasut <marex@...x.de>,
        David Airlie <airlied@...ux.ie>,
        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

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>

	Sam