From: Mark Brown <broonie@kernel.org>
To: Javier Martinez Canillas <javierm@redhat.com>
Cc: linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Chen-Yu Tsai <wens@kernel.org>,
Geert Uytterhoeven <geert@linux-m68k.org>,
Chen-Yu Tsai <wens@csie.org>, Daniel Vetter <daniel@ffwll.ch>,
David Airlie <airlied@linux.ie>,
Maxime Ripard <maxime@cerno.tech>,
YueHaibing <yuehaibing@huawei.com>
Subject: Re: [PATCH 5/5] drm/solomon: Add SSD130x OLED displays SPI support
Date: Fri, 8 Apr 2022 12:18:06 +0100 [thread overview]
Message-ID: <YlAZ7gl7aHjIrYn9@sirena.org.uk> (raw)
In-Reply-To: <20220407200205.28838-6-javierm@redhat.com>
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On Thu, Apr 07, 2022 at 10:02:04PM +0200, Javier Martinez Canillas wrote:
> The ssd130x driver only provides the core support for these devices but it
> does not have any bus transport logic. Add a driver to interface over SPI.
>
> There is a difference in the communication protocol when using 4-wire SPI
> instead of I2C. For the latter, a control byte that contains a D/C# field
> has to be sent. This field tells the controller whether the data has to be
> written to the command register or to the graphics display data memory.
>
> But for 4-wire SPI that control byte is not used, instead a real D/C# line
> must be pulled HIGH for commands data and LOW for graphics display data.
>
> For this reason the standard SPI regmap can't be used and a custom .write
> bus handler is needed.
Acked-by: Mark Brown <broonie@kernel.org>
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prev parent reply other threads:[~2022-04-08 11:18 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-07 20:01 [PATCH 0/5] " Javier Martinez Canillas
2022-04-07 20:02 ` [PATCH 1/5] dt-bindings: display: ssd1307fb: Deprecate fbdev compatible strings Javier Martinez Canillas
2022-04-08 18:22 ` Rob Herring
2022-04-08 19:19 ` Javier Martinez Canillas
2022-04-08 19:25 ` Javier Martinez Canillas
2022-04-11 13:47 ` Geert Uytterhoeven
2022-04-11 14:48 ` Javier Martinez Canillas
2022-04-07 20:02 ` [PATCH 2/5] dt-bindings: display: ssd1307fb: Extend schema for SPI controllers Javier Martinez Canillas
2022-04-07 20:02 ` [PATCH 3/5] drm/solomon: Add ssd130x-i2c compatible strings without an -fb suffix Javier Martinez Canillas
2022-04-07 20:02 ` [PATCH 4/5] drm/solomon: Move device info from ssd130x-i2c to the core driver Javier Martinez Canillas
2022-04-08 7:49 ` Neil Armstrong
2022-04-08 8:23 ` Javier Martinez Canillas
2022-04-07 20:02 ` [PATCH 5/5] drm/solomon: Add SSD130x OLED displays SPI support Javier Martinez Canillas
2022-04-08 11:18 ` Mark Brown [this message]
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