linux-kernel - Re: [PATCH 2/2] media: qcom: camss: Restrict endpoint bus-type to D-PHY

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Message-ID: <8308a825-2f33-4ec6-bfd2-9d3ed31c4a56@linaro.org>
Date: Fri, 13 Dec 2024 19:58:20 +0200
From: Vladimir Zapolskiy <vladimir.zapolskiy@...aro.org>
To: Luca Weiss <luca.weiss@...rphone.com>, Robert Foss <rfoss@...nel.org>,
 Todor Tomov <todor.too@...il.com>,
 Bryan O'Donoghue <bryan.odonoghue@...aro.org>,
 Mauro Carvalho Chehab <mchehab@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Barnabas Czeman <barnabas.czeman@...nlining.org>,
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...ainline.org>,
 Caleb Connolly <caleb.connolly@...aro.org>, David Heidelberg <david@...t.cz>
Cc: ~postmarketos/upstreaming@...ts.sr.ht, phone-devel@...r.kernel.org,
 linux-arm-msm@...r.kernel.org, linux-media@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] media: qcom: camss: Restrict endpoint bus-type to
 D-PHY

Hi Luca.

On 12/9/24 14:01, Luca Weiss wrote:
> Currently the Qualcomm CAMSS driver only supports D-PHY while the
> hardware on most SoCs also supports C-PHY. Until this support is added,
> check for D-PHY to make it somewhat explicit that C-PHY won't work.
> 
> Signed-off-by: Luca Weiss <luca.weiss@...rphone.com>
> ---
>   drivers/media/platform/qcom/camss/camss.c | 9 +++++++++
>   1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/media/platform/qcom/camss/camss.c b/drivers/media/platform/qcom/camss/camss.c
> index 9fb31f4c18adee886cd0bcf84438a8f27635e07f..b99af35074cdf6fa794a0d2f0d54ecf12ac354d9 100644
> --- a/drivers/media/platform/qcom/camss/camss.c
> +++ b/drivers/media/platform/qcom/camss/camss.c
> @@ -1855,6 +1855,15 @@ static int camss_of_parse_endpoint_node(struct device *dev,
>   	if (ret)
>   		return ret;
>   
> +	/*
> +	 * Most SoCs support both D-PHY and C-PHY standards, but currently only
> +	 * D-PHY is supported in the driver.
> +	 */
> +	if (vep.bus_type != V4L2_MBUS_CSI2_DPHY) {
> +		dev_err(dev, "Unsupported bus type %d\n", vep.bus_type);
> +		return -EINVAL;
> +	}
> +
>   	csd->interface.csiphy_id = vep.base.port;
>   
>   	mipi_csi2 = &vep.bus.mipi_csi2;

My cautious worries were futile, the change works as expected and
the regression testing on RB5 is passed:

===== begin parsing endpoint /soc@...amss@...a000/ports/port@...ndpoint
fwnode video bus type not specified (0), mbus type not specified (0)
lane 0 position 0
lane 1 position 1
lane 2 position 2
lane 3 position 3
clock lane position 7
no lane polarities defined, assuming not inverted
assuming media bus type MIPI CSI-2 D-PHY (5)
===== end parsing endpoint /soc@...amss@...a000/ports/port@...ndpoint

Tested-by: Vladimir Zapolskiy <vladimir.zapolskiy@...aro.org>
Reviewed-by: Vladimir Zapolskiy <vladimir.zapolskiy@...aro.org>

--
Best wishes,
Vladimir