linux-kernel - Re: [PATCH v1 2/3] drm/panel: st7701: Add support for SPI for configuration

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Date: Tue, 18 Jun 2024 11:20:20 +0200
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Hironori KIKUCHI <kikuchan98@...il.com>, linux-kernel@...r.kernel.org
Cc: Jagan Teki <jagan@...rulasolutions.com>,
 Neil Armstrong <neil.armstrong@...aro.org>,
 Jessica Zhang <quic_jesszhan@...cinc.com>, Sam Ravnborg <sam@...nborg.org>,
 David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>, dri-devel@...ts.freedesktop.org,
 devicetree@...r.kernel.org
Subject: Re: [PATCH v1 2/3] drm/panel: st7701: Add support for SPI for
 configuration

On 18/06/2024 10:15, Hironori KIKUCHI wrote:
> The ST7701 supports not only MIPI DSI, but also SPI as an interface
> for configuration. To support a panel connected via RGB parallel
> interface, add support for SPI using MIPI DBI helpers.
> 
> Signed-off-by: Hironori KIKUCHI <kikuchan98@...il.com>


...

> +
> +static int st7701_spi_probe(struct spi_device *spi)
> +{
> +	struct st7701 *st7701;
> +	struct gpio_desc *dc;
> +	int err;
> +
> +	err = st7701_probe(&spi->dev, DRM_MODE_CONNECTOR_DPI);
> +	if (err)
> +		return err;
> +
> +	st7701 = dev_get_drvdata(&spi->dev);
> +	st7701->write_command = st7701_dbi_write;
> +
> +	dc = devm_gpiod_get_optional(&spi->dev, "dc", GPIOD_OUT_LOW | GPIOD_FLAGS_BIT_NONEXCLUSIVE);

Nope, you cannot use GPIOD_FLAGS_BIT_NONEXCLUSIVE outside of regulators.
I don't see any code for ensuring proper simultaneus access.

Best regards,
Krzysztof