linux-kernel - Re: [PATCH v2 3/3] drm/panel-fannal-c3003: Add fannal c3004 DSI panel

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Date:   Tue, 6 Jun 2023 16:52:55 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Paulo Pavacic <pavacic.p@...il.com>
Cc:     neil.armstrong@...aro.org, sam@...nborg.org, airlied@...il.com,
        daniel@...ll.ch, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH v2 3/3] drm/panel-fannal-c3003: Add fannal c3004 DSI panel

On 06/06/2023 09:36, Paulo Pavacic wrote:
>>> +
>>> +     if (IS_ERR(panel_data->reset)) {
>>> +             ret = PTR_ERR(panel_data->reset);
>>> +             dev_err(dev,
>>> +                     "error: probe: get reset GPIO: (%d) Check the fdt\n",
>>> +                     ret);
>>
>> return dev_err_probe
>>
>>> +             return ret;
>>> +     }
>>> +
>>> +     mipi_dsi_set_drvdata(dsi, panel_data);
>>> +
>>> +     dsi->format = MIPI_DSI_FMT_RGB888;
>>> +     dsi->mode_flags = MIPI_DSI_CLOCK_NON_CONTINUOUS |
>>> +                       MIPI_DSI_MODE_VSYNC_FLUSH | MIPI_DSI_MODE_VIDEO_HSE |
>>> +                       MIPI_DSI_MODE_NO_EOT_PACKET |
>>> +                       MIPI_DSI_MODE_VIDEO_SYNC_PULSE | MIPI_DSI_MODE_VIDEO;
>>> +     dsi->lanes = 2;
>>> +
>>> +     gpiod_set_value_cansleep(panel_data->reset, 1);
>>
>> So you leave the panel in reset state?
> yes

Then why do you initialize GPIO to bring it out of reset and them
immediately put into reset back? Just keep it in reset.

Best regards,
Krzysztof