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SubjectRe: [PATCH v3 3/9] drm/bridge: ti-sn65dsi86: Don't use MIPI variables for DP link
On Wed 18 Dec 14:35 PST 2019, Douglas Anderson wrote:

> The ti-sn65dsi86 is a bridge from MIPI to DP and thus has two links:
> the MIPI link and the DP link. The two links do not need to have the
> same format or number of lanes. Stop using MIPI variables when
> talking about the DP link.
>
> This has zero functional change because:
> * currently we are hardcoding the MIPI link as unpacked RGB888 which
> requires 24 bits and currently we are not changing the DP link rate
> from the bridge's default of 8 bits per pixel.
> * currently we are hardcoding both the MIPI and DP as being 4 lanes.
>
> This is all in prep for fixing some of the above.
>
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> Tested-by: Rob Clark <robdclark@gmail.com>
> Reviewed-by: Rob Clark <robdclark@gmail.com>

Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>

> ---
>
> Changes in v3: None
> Changes in v2: None
>
> drivers/gpu/drm/bridge/ti-sn65dsi86.c | 18 ++++++++++++------
> 1 file changed, 12 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> index 7b596af265e4..ab644baaf90c 100644
> --- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> @@ -100,6 +100,7 @@ struct ti_sn_bridge {
> struct drm_panel *panel;
> struct gpio_desc *enable_gpio;
> struct regulator_bulk_data supplies[SN_REGULATOR_SUPPLY_NUM];
> + int dp_lanes;
> };
>
> static const struct regmap_range ti_sn_bridge_volatile_ranges[] = {
> @@ -313,6 +314,7 @@ static int ti_sn_bridge_attach(struct drm_bridge *bridge)
> }
>
> /* TODO: setting to 4 lanes always for now */
> + pdata->dp_lanes = 4;
> dsi->lanes = 4;
> dsi->format = MIPI_DSI_FMT_RGB888;
> dsi->mode_flags = MIPI_DSI_MODE_VIDEO;
> @@ -451,13 +453,17 @@ static void ti_sn_bridge_set_dp_rate(struct ti_sn_bridge *pdata)
> struct drm_display_mode *mode =
> &pdata->bridge.encoder->crtc->state->adjusted_mode;
>
> - /* set DSIA clk frequency */
> - bit_rate_mhz = (mode->clock / 1000) *
> - mipi_dsi_pixel_format_to_bpp(pdata->dsi->format);
> + /*
> + * Calculate minimum bit rate based on our pixel clock. At
> + * the moment this driver never sets the DP_18BPP_EN bit in
> + * register 0x5b so we hardcode 24bpp.
> + */
> + bit_rate_mhz = (mode->clock / 1000) * 24;
>
> - /* set DP data rate */
> - dp_rate_mhz = ((bit_rate_mhz / pdata->dsi->lanes) * DP_CLK_FUDGE_NUM) /
> + /* Calculate minimum DP data rate, taking 80% as per DP spec */
> + dp_rate_mhz = ((bit_rate_mhz / pdata->dp_lanes) * DP_CLK_FUDGE_NUM) /
> DP_CLK_FUDGE_DEN;
> +
> for (i = 1; i < ARRAY_SIZE(ti_sn_bridge_dp_rate_lut) - 1; i++)
> if (ti_sn_bridge_dp_rate_lut[i] > dp_rate_mhz)
> break;
> @@ -517,7 +523,7 @@ static void ti_sn_bridge_enable(struct drm_bridge *bridge)
> CHA_DSI_LANES_MASK, val);
>
> /* DP lane config */
> - val = DP_NUM_LANES(pdata->dsi->lanes - 1);
> + val = DP_NUM_LANES(pdata->dp_lanes - 1);
> regmap_update_bits(pdata->regmap, SN_SSC_CONFIG_REG, DP_NUM_LANES_MASK,
> val);
>
> --
> 2.24.1.735.g03f4e72817-goog
>

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