Re: [PATCH 4/4] drm/panel: samsung-s6e88a0-ams427ap24: Add flip option

Jessica Zhang
2024-10-11T17:18:07Z

On 10/10/2024 11:31 AM, Jakob Hauser wrote:
> The way of implementing a flip option follows the existing
> panel-samsung-s6e8aa0.c [1][2][3].
>
> The value to flip the screen is taken from a downstream kernel file of
> a similar but older panel [4]. The mipi clock [5] for the new panel
> samsung-s6e88a0-ams427ap24 matches 461 MHz and a hardware read-out of the
> 0xcb values corresponds to revision R01 of that older panel [6]. Although
> for samsung-s6e88a0-ams427ap24 that's in non-flipped state while in this
> older driver it seems to be the other way around. Further up there is a

Hi Jakob,

I'm a bit confused by the wording here. Do you mean that even though the
downstream driver comments state the panel is in a non-flipped state by
default, your observations suggest that it's actually defaulting to a
flipped state?

Thanks,

Jessica Zhang

> hint [7] basically saying for revision R01 to change the first word of the
> 0xcb command from 0x06 to 0x0e, which is actually setting BIT(3) of that
> word. This causes a horizontal flip.
>
> [1] https://github.com/torvalds/linux/blob/v6.11/drivers/gpu/drm/panel/panel-samsung-s6e8aa0.c#L103
> [2] https://github.com/torvalds/linux/blob/v6.11/drivers/gpu/drm/panel/panel-samsung-s6e8aa0.c#L207-L211
> [3] https://github.com/torvalds/linux/blob/v6.11/drivers/gpu/drm/panel/panel-samsung-s6e8aa0.c#L954-L974
> [4] https://github.com/LineageOS/android_kernel_samsung_msm8930-common/blob/lineage-15.1/drivers/video/msm/mipi_samsung_oled_video_qhd_pt-8930.c
> [5] https://github.com/LineageOS/android_kernel_samsung_msm8930-common/blob/lineage-15.1/drivers/video/msm/mipi_samsung_oled_video_qhd_pt-8930.c#L2027-L2028
> [6] https://github.com/LineageOS/android_kernel_samsung_msm8930-common/blob/lineage-15.1/drivers/video/msm/mipi_samsung_oled_video_qhd_pt-8930.c#L137-L151
> [7] https://github.com/LineageOS/android_kernel_samsung_msm8930-common/blob/lineage-15.1/drivers/video/msm/mipi_samsung_oled_video_qhd_pt-8930.c#L66-L74
>
> Signed-off-by: Jakob Hauser <jahau@rocketmail.com>
> ---
> .../drm/panel/panel-samsung-s6e88a0-ams427ap24.c | 16 ++++++++++++++++
> 1 file changed, 16 insertions(+)
>
> diff --git a/drivers/gpu/drm/panel/panel-samsung-s6e88a0-ams427ap24.c b/drivers/gpu/drm/panel/panel-samsung-s6e88a0-ams427ap24.c
> index 657120d7dd33..4d5c494e03ae 100644
> --- a/drivers/gpu/drm/panel/panel-samsung-s6e88a0-ams427ap24.c
> +++ b/drivers/gpu/drm/panel/panel-samsung-s6e88a0-ams427ap24.c
> @@ -32,6 +32,7 @@ struct s6e88a0_ams427ap24 {
> struct mipi_dsi_device *dsi;
> struct regulator_bulk_data *supplies;
> struct gpio_desc *reset_gpio;
> + bool flip_horizontal;
> bool prepared;
> };
>
> @@ -539,6 +540,10 @@ static int s6e88a0_ams427ap24_on(struct s6e88a0_ams427ap24 *ctx)
> mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xcc, 0x4c);
> mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xf2, 0x03, 0x0d);
> mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xf1, 0xa5, 0xa5);
> +
> + if (ctx->flip_horizontal)
> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xcb, 0x0e);
> +
> mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xf0, 0xa5, 0xa5);
> mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xfc, 0xa5, 0xa5);
>
> @@ -673,6 +678,15 @@ static int s6e88a0_ams427ap24_register_backlight(struct s6e88a0_ams427ap24 *ctx)
> return ret;
> }
>
> +static void s6e88a0_ams427ap24_parse_dt(struct s6e88a0_ams427ap24 *ctx)
> +{
> + struct mipi_dsi_device *dsi = ctx->dsi;
> + struct device *dev = &dsi->dev;
> + struct device_node *np = dev->of_node;
> +
> + ctx->flip_horizontal = of_property_read_bool(np, "flip-horizontal");
> +}
> +
> static int s6e88a0_ams427ap24_probe(struct mipi_dsi_device *dsi)
> {
> struct device *dev = &dsi->dev;
> @@ -707,6 +721,8 @@ static int s6e88a0_ams427ap24_probe(struct mipi_dsi_device *dsi)
> DRM_MODE_CONNECTOR_DSI);
> ctx->panel.prepare_prev_first = true;
>
> + s6e88a0_ams427ap24_parse_dt(ctx);
> +
> ret = s6e88a0_ams427ap24_register_backlight(ctx);
> if (ret < 0)
> return ret;
> --
> 2.39.5
>