linux-kernel - Re: [PATCH v11 6/9] drm/bridge: anx7625: Register Type C mode switches

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Message-ID: <20230217153150.tl3zqywvpw6elyg5@notapiano>
Date:   Fri, 17 Feb 2023 10:31:50 -0500
From:   Nícolas F. R. A. Prado 
        <nfraprado@...labora.com>
To:     Pin-yen Lin <treapking@...omium.org>
Cc:     Andrzej Hajda <andrzej.hajda@...el.com>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        Robert Foss <robert.foss@...aro.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Daniel Scally <djrscally@...il.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Prashant Malani <pmalani@...omium.org>,
        Benson Leung <bleung@...omium.org>,
        Guenter Roeck <groeck@...omium.org>,
        linux-kernel@...r.kernel.org, Hsin-Yi Wang <hsinyi@...omium.org>,
        devicetree@...r.kernel.org, Allen Chen <allen.chen@....com.tw>,
        Lyude Paul <lyude@...hat.com>, linux-acpi@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, Marek Vasut <marex@...x.de>,
        Xin Ji <xji@...logixsemi.com>,
        Stephen Boyd <swboyd@...omium.org>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Javier Martinez Canillas <javierm@...hat.com>,
        chrome-platform@...ts.linux.dev,
        José Expósito <jose.exposito89@...il.com>
Subject: Re: [PATCH v11 6/9] drm/bridge: anx7625: Register Type C mode
 switches

On Sat, Feb 04, 2023 at 09:30:37PM +0800, Pin-yen Lin wrote:
[..]
> --- a/drivers/gpu/drm/bridge/analogix/anx7625.c
> +++ b/drivers/gpu/drm/bridge/analogix/anx7625.c
[..]
> +static void anx7625_set_crosspoint_switch(struct anx7625_data *ctx,
> +					  enum typec_orientation orientation)
> +{
> +	if (orientation == TYPEC_ORIENTATION_NORMAL) {
> +		anx7625_reg_write(ctx, ctx->i2c.tcpc_client, TCPC_SWITCH_0,
> +				  SW_SEL1_SSRX_RX1 | SW_SEL1_DPTX0_RX2);
> +		anx7625_reg_write(ctx, ctx->i2c.tcpc_client, TCPC_SWITCH_1,
> +				  SW_SEL2_SSTX_TX1 | SW_SEL2_DPTX1_TX2);

This seems inverted compared to the binding. Binding says 

  0, 1, 2, 3 in "data-lanes" maps to SSRX1, SSTX1, SSRX2, SSTX2, respectively.

But in anx7625_register_typec_switches(), lanes 0-1 mean orientation normal,
then in this logic, you set RX2 and TX2 to carry the DP signals. So the driver
is mapping lanes 0-1 to SSRX2/SSTX2 and lanes 2-3 to SSRX1/SSTX1, the opposite
from the binding.

Thanks,
Nícolas

> +	} else if (orientation == TYPEC_ORIENTATION_REVERSE) {
> +		anx7625_reg_write(ctx, ctx->i2c.tcpc_client, TCPC_SWITCH_0,
> +				  SW_SEL1_SSRX_RX2 | SW_SEL1_DPTX0_RX1);
> +		anx7625_reg_write(ctx, ctx->i2c.tcpc_client, TCPC_SWITCH_1,
> +				  SW_SEL2_SSTX_TX2 | SW_SEL2_DPTX1_TX1);
> +	}
> +}
> +
[..]
> +static int anx7625_register_typec_switches(struct device *dev, struct anx7625_data *ctx)
> +{
[..]
> +		ctx->port_data[i].orientation = (dp_lanes[0] / 2 == 0) ?
> +			TYPEC_ORIENTATION_NORMAL : TYPEC_ORIENTATION_REVERSE;
[..]