linux-kernel - Re: [PATCH v2 7/7] drm/bridge: anx7625: Add typec_mux

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Date:   Tue, 14 Jun 2022 10:15:31 +0200
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     Prashant Malani <pmalani@...omium.org>,
        linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org
Cc:     heikki.krogerus@...ux.intel.com,
        Andrzej Hajda <andrzej.hajda@...el.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        David Airlie <airlied@...ux.ie>,
        "open list:DRM DRIVERS" <dri-devel@...ts.freedesktop.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Sam Ravnborg <sam@...nborg.org>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Tzung-Bi Shih <tzungbi@...gle.com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Nícolas F. R. A. Prado 
        <nfraprado@...labora.com>, Jonas Karlman <jonas@...boo.se>,
        swboyd@...omium.org, Pin-Yen Lin <treapking@...omium.org>,
        Rob Herring <robh+dt@...nel.org>,
        Maxime Ripard <maxime@...no.tech>,
        Hsin-Yi Wang <hsinyi@...omium.org>,
        Xin Ji <xji@...logixsemi.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Robert Foss <robert.foss@...aro.org>,
        José Expósito <jose.exposito89@...il.com>
Subject: Re: [PATCH v2 7/7] drm/bridge: anx7625: Add typec_mux_set callback
 function

Il 09/06/22 20:09, Prashant Malani ha scritto:
> From: Pin-Yen Lin <treapking@...omium.org>
> 
> Add the callback function when the driver receives state
> changes of the Type-C port. The callback function configures the
> crosspoint switch of the anx7625 bridge chip, which can change the
> output pins of the signals according to the port state.
> 
> Signed-off-by: Pin-Yen Lin <treapking@...omium.org>
> Signed-off-by: Prashant Malani <pmalani@...omium.org>
> ---
> 
> Changes since v2:
> - No changes.
> 
>   drivers/gpu/drm/bridge/analogix/anx7625.c | 58 +++++++++++++++++++++++
>   drivers/gpu/drm/bridge/analogix/anx7625.h | 13 +++++
>   2 files changed, 71 insertions(+)
> 
> diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.c b/drivers/gpu/drm/bridge/analogix/anx7625.c
> index d41a21103bd3..2c308d12fab2 100644
> --- a/drivers/gpu/drm/bridge/analogix/anx7625.c
> +++ b/drivers/gpu/drm/bridge/analogix/anx7625.c
> @@ -15,6 +15,7 @@
>   #include <linux/regulator/consumer.h>
>   #include <linux/slab.h>
>   #include <linux/types.h>
> +#include <linux/usb/typec_dp.h>
>   #include <linux/usb/typec_mux.h>
>   #include <linux/workqueue.h>
>   
> @@ -2582,9 +2583,66 @@ static void anx7625_runtime_disable(void *data)
>   	pm_runtime_disable(data);
>   }
>   
> +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);
> +	} 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 void anx7625_typec_two_ports_update(struct anx7625_data *ctx)
> +{
> +	if (ctx->typec_ports[0].dp_connected && ctx->typec_ports[1].dp_connected)
> +		/* Both ports available, do nothing to retain the current one. */
> +		return;
> +	else if (ctx->typec_ports[0].dp_connected)
> +		anx7625_set_crosspoint_switch(ctx, TYPEC_ORIENTATION_NORMAL);
> +	else if (ctx->typec_ports[1].dp_connected)
> +		anx7625_set_crosspoint_switch(ctx, TYPEC_ORIENTATION_REVERSE);
> +}
> +
>   static int anx7625_typec_mux_set(struct typec_mux_dev *mux,
>   				 struct typec_mux_state *state)
>   {
> +	struct anx7625_port_data *data = typec_mux_get_drvdata(mux);
> +	struct anx7625_data *ctx = data->ctx;
> +	struct device *dev = &ctx->client->dev;
> +
> +	bool old_dp_connected = (ctx->typec_ports[0].dp_connected ||
> +				 ctx->typec_ports[1].dp_connected);

So the old connection state is "either port0 or port1 are currently connected"...

> +	bool new_dp_connected;
> +
> +	if (ctx->num_typec_switches == 1)
> +		return 0;
> +
> +	dev_dbg(dev, "mux_set dp_connected: c0=%d, c1=%d\n",
> +		ctx->typec_ports[0].dp_connected, ctx->typec_ports[1].dp_connected);
> +
> +	data->dp_connected = (state->alt && state->alt->svid == USB_TYPEC_DP_SID &&
> +			      state->alt->mode == USB_TYPEC_DP_MODE);
> + > +	new_dp_connected = (ctx->typec_ports[0].dp_connected ||
> +			    ctx->typec_ports[1].dp_connected);

...and the new connection state is the same as the old one, because I don't see
anything that could ever modify it in this function's flow, until reaching this
assignment.

> +
> +	/* dp on, power on first */
> +	if (!old_dp_connected && new_dp_connected)
> +		pm_runtime_get_sync(dev);

...so that will never happen...

> +
> +	anx7625_typec_two_ports_update(ctx);
> +
> +	/* dp off, power off last */
> +	if (old_dp_connected && !new_dp_connected)
> +		pm_runtime_put_sync(dev);

...and same here.

Regards,
Angelo