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Date: Wed, 15 Jun 2022 15:57:55 +0200
From: AngeloGioacchino Del Regno
<angelogioacchino.delregno@...labora.com>
To: Prashant Malani <pmalani@...omium.org>,
Pin-yen Lin <treapking@...omium.org>
Cc: linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
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, 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 14/06/22 18:58, Prashant Malani ha scritto:
> On Tue, Jun 14, 2022 at 2:08 AM Pin-yen Lin <treapking@...omium.org> wrote:
>>
>> Hi AngeloGioacchino,
>>
>>
>> On Tue, Jun 14, 2022 at 4:15 PM AngeloGioacchino Del Regno
>> <angelogioacchino.delregno@...labora.com> wrote:
>>>
>>> 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.
>>
>> The typec mux driver data (`struct anx7625_port_data *data =
>> typec_mux_get_drvdata(mux)`) is set to one of the
>> `ctx->typec_ports[*]` in `anx7625_register_mode_switch` (see patch 6
>> of this series).
>>
>> So, the `data->dp_connected = ...` assignment may change the new
>> connection state.
>
> Angelo, I think your interpretation of this logic is not accurate..
> |old_dp_connected| represents *whether* port1 or port0 has a DP
> partner connected, not that *either* of them has it.
>
> So, this logic looks OK to me.
>
Hello Prashant,
You're completely right: I've finally seen where this is happening, so yes
we don't know, nor care at that moment, whether data->dp_connected is port0
or port1, we assign and check 'em both again, which is actually smart.
I'm sorry for the misunderstandment - and thank you for your reply.
Feel free to add my
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
Regards,
Angelo
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