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Date: Thu, 17 Feb 2022 09:34:59 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Kuogee Hsieh <quic_khsieh@...cinc.com>,
dri-devel@...ts.freedesktop.org, robdclark@...il.com,
sean@...rly.run, swboyd@...omium.org, vkoul@...nel.org,
daniel@...ll.ch, airlied@...ux.ie, agross@...nel.org,
bjorn.andersson@...aro.org
Cc: quic_abhinavk@...cinc.com, quic_aravindh@...cinc.com,
quic_sbillaka@...cinc.com, freedreno@...ts.freedesktop.org,
linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 1/4] drm/msm/dpu: revise timing engine programming to
support widebus feature
On 17/02/2022 01:05, Kuogee Hsieh wrote:
> Widebus feature will transmit two pixel data per pixel clock to interface.
> Timing engine provides driving force for this purpose. This patch base
> on HPG (Hardware Programming Guide) to revise timing engine register
> setting to accommodate both widebus and non widebus application. Also
> horizontal width parameters need to be reduced by half since two pixel
> data are clocked out per pixel clock when widebus feature enabled.
>
> Widebus can be enabled individually at DP. However at DSI, widebus have
> to be enabled along with DSC to achieve pixel clock rate be scaled down
> with same ratio as compression ratio when 10 bits per source component.
> Therefore this patch add no supports of DSI related widebus and compression.
>
> Changes in v2:
> -- remove compression related code from timing
> -- remove op_info from struct msm_drm_private
> -- remove unnecessary wide_bus_en variables
> -- pass wide_bus_en into timing configuration by struct msm_dp
>
> Changes in v3:
> -- split patch into 3 patches
>
> Changes in v4:
> -- rework timing engine to not interfere with dsi/hdmi
> -- cover both widebus and compression
>
> Changes in v5:
> -- remove supports of DSI widebus and compression
>
> Changes in v7:
> -- split this patch into 3 patches
> -- add Tested-by
>
> Signed-off-by: Kuogee Hsieh <quic_khsieh@...cinc.com>
> Tested-by: Bjorn Andersson <bjorn.andersson@...aro.org>
> ---
> drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 10 ++++
> drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h | 2 +
> .../gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c | 14 ++++++
> drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c | 55 ++++++++++++++++------
> drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.h | 2 +
> 5 files changed, 68 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> index 1e648db..2b2dbb7 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> @@ -208,6 +208,8 @@ struct dpu_encoder_virt {
>
> u32 idle_timeout;
>
> + bool wide_bus_en;
> +
> struct msm_dp *dp;
> };
>
> @@ -217,6 +219,14 @@ static u32 dither_matrix[DITHER_MATRIX_SZ] = {
> 15, 7, 13, 5, 3, 11, 1, 9, 12, 4, 14, 6, 0, 8, 2, 10
> };
>
> +
> +bool dpu_encoder_is_widebus_enabled(struct drm_encoder *drm_enc)
> +{
> + struct dpu_encoder_virt *dpu_enc = to_dpu_encoder_virt(drm_enc);
> +
> + return dpu_enc->wide_bus_en;
> +}
> +
> static void _dpu_encoder_setup_dither(struct dpu_hw_pingpong *hw_pp, unsigned bpc)
> {
> struct dpu_hw_dither_cfg dither_cfg = { 0 };
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
> index e241914..0d73550 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
> @@ -168,4 +168,6 @@ int dpu_encoder_get_linecount(struct drm_encoder *drm_enc);
> */
> int dpu_encoder_get_vsync_count(struct drm_encoder *drm_enc);
>
> +bool dpu_encoder_is_widebus_enabled(struct drm_encoder *drm_enc);
> +
> #endif /* __DPU_ENCODER_H__ */
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
> index ddd9d89..04ac2dc 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
> @@ -110,6 +110,20 @@ static void drm_mode_to_intf_timing_params(
> timing->v_back_porch += timing->v_front_porch;
> timing->v_front_porch = 0;
> }
> +
> + timing->wide_bus_en = dpu_encoder_is_widebus_enabled(phys_enc->parent);
> +
> + /*
> + * for DP, divide the horizonal parameters by 2 when
> + * widebus is enabled
> + */
> + if (phys_enc->hw_intf->cap->type == INTF_DP && timing->wide_bus_en) {
> + timing->width = timing->width >> 1;
> + timing->xres = timing->xres >> 1;
> + timing->h_back_porch = timing->h_back_porch >> 1;
> + timing->h_front_porch = timing->h_front_porch >> 1;
> + timing->hsync_pulse_width = timing->hsync_pulse_width >> 1;
> + }
> }
>
> static u32 get_horizontal_total(const struct intf_timing_params *timing)
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c
> index 116e2b5..b68e696 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c
> @@ -33,6 +33,7 @@
> #define INTF_TP_COLOR1 0x05C
> #define INTF_CONFIG2 0x060
> #define INTF_DISPLAY_DATA_HCTL 0x064
> +#define INTF_ACTIVE_DATA_HCTL 0x068
> #define INTF_FRAME_LINE_COUNT_EN 0x0A8
> #define INTF_FRAME_COUNT 0x0AC
> #define INTF_LINE_COUNT 0x0B0
> @@ -90,15 +91,23 @@ static void dpu_hw_intf_setup_timing_engine(struct dpu_hw_intf *ctx,
> u32 hsync_period, vsync_period;
> u32 display_v_start, display_v_end;
> u32 hsync_start_x, hsync_end_x;
> + u32 hsync_data_start_x, hsync_data_end_x;
> u32 active_h_start, active_h_end;
> u32 active_v_start, active_v_end;
> u32 active_hctl, display_hctl, hsync_ctl;
> u32 polarity_ctl, den_polarity, hsync_polarity, vsync_polarity;
> u32 panel_format;
> - u32 intf_cfg, intf_cfg2 = 0, display_data_hctl = 0;
> + u32 intf_cfg, intf_cfg2 = 0;
> + u32 display_data_hctl = 0, active_data_hctl = 0;
> + u32 data_width;
> + bool dp_intf = false;
>
> /* read interface_cfg */
> intf_cfg = DPU_REG_READ(c, INTF_CONFIG);
> +
> + if (ctx->cap->type == INTF_EDP || ctx->cap->type == INTF_DP)
> + dp_intf = true;
> +
> hsync_period = p->hsync_pulse_width + p->h_back_porch + p->width +
> p->h_front_porch;
> vsync_period = p->vsync_pulse_width + p->v_back_porch + p->height +
> @@ -112,7 +121,7 @@ static void dpu_hw_intf_setup_timing_engine(struct dpu_hw_intf *ctx,
> hsync_start_x = p->h_back_porch + p->hsync_pulse_width;
> hsync_end_x = hsync_period - p->h_front_porch - 1;
>
> - if (p->width != p->xres) {
> + if (p->width != p->xres) { /* border fill added */
> active_h_start = hsync_start_x;
> active_h_end = active_h_start + p->xres - 1;
> } else {
> @@ -120,7 +129,7 @@ static void dpu_hw_intf_setup_timing_engine(struct dpu_hw_intf *ctx,
> active_h_end = 0;
> }
>
> - if (p->height != p->yres) {
> + if (p->height != p->yres) { /* border fill added */
> active_v_start = display_v_start;
> active_v_end = active_v_start + (p->yres * hsync_period) - 1;
> } else {
> @@ -130,27 +139,47 @@ static void dpu_hw_intf_setup_timing_engine(struct dpu_hw_intf *ctx,
>
> if (active_h_end) {
> active_hctl = (active_h_end << 16) | active_h_start;
> - intf_cfg |= BIT(29); /* ACTIVE_H_ENABLE */
> + intf_cfg |= BIT(29);
> } else {
> active_hctl = 0;
> }
>
> if (active_v_end)
> - intf_cfg |= BIT(30); /* ACTIVE_V_ENABLE */
> + intf_cfg |= BIT(30);
>
> hsync_ctl = (hsync_period << 16) | p->hsync_pulse_width;
> display_hctl = (hsync_end_x << 16) | hsync_start_x;
>
> - if (ctx->cap->type == INTF_EDP || ctx->cap->type == INTF_DP) {
> + /*
> + * DATA_HCTL_EN controls data timing which can be different from
> + * video timing. It is recommended to enable it for all cases, except
> + * if compression is enabled in 1 pixel per clock mode
> + */
> + if (p->wide_bus_en)
> + intf_cfg2 |= (BIT(0) | BIT(4));
Previously the HCTL_EN was set even for non-wide-bus cases. Was this
incorrect? Should we set it only for the wide bus case?
> +
> + data_width = p->width;
> +
> + hsync_data_start_x = hsync_start_x;
> + hsync_data_end_x = hsync_start_x + data_width - 1;
> +
> + display_data_hctl = (hsync_data_end_x << 16) | hsync_data_start_x;
> +
> + if (dp_intf) {
> + /* DP timing adjustment */
> + display_v_start += p->hsync_pulse_width + p->h_back_porch;
> + display_v_end -= p->h_front_porch;
Quoting a question to v4:
So, this changes the display_v_end. Is there a mistake currently (and
so this change should be backported to stable kernels) or is it just
unoptimal?
> +
> active_h_start = hsync_start_x;
> active_h_end = active_h_start + p->xres - 1;
> active_v_start = display_v_start;
> active_v_end = active_v_start + (p->yres * hsync_period) - 1;
>
> - display_v_start += p->hsync_pulse_width + p->h_back_porch;
> -
> active_hctl = (active_h_end << 16) | active_h_start;
> display_hctl = active_hctl;
> +
> + intf_cfg |= BIT(29);
> + intf_cfg |= BIT(30);
Could you please add defines for _new_ bits in this patch.
> }
>
> den_polarity = 0;
> @@ -180,13 +209,6 @@ static void dpu_hw_intf_setup_timing_engine(struct dpu_hw_intf *ctx,
> (COLOR_8BIT << 4) |
> (0x21 << 8));
>
> - if (ctx->cap->features & BIT(DPU_DATA_HCTL_EN)) {
> - intf_cfg2 |= BIT(4);
> - display_data_hctl = display_hctl;
> - DPU_REG_WRITE(c, INTF_CONFIG2, intf_cfg2);
> - DPU_REG_WRITE(c, INTF_DISPLAY_DATA_HCTL, display_data_hctl);
> - }
> -
> DPU_REG_WRITE(c, INTF_HSYNC_CTL, hsync_ctl);
> DPU_REG_WRITE(c, INTF_VSYNC_PERIOD_F0, vsync_period * hsync_period);
> DPU_REG_WRITE(c, INTF_VSYNC_PULSE_WIDTH_F0,
> @@ -204,6 +226,9 @@ static void dpu_hw_intf_setup_timing_engine(struct dpu_hw_intf *ctx,
> DPU_REG_WRITE(c, INTF_FRAME_LINE_COUNT_EN, 0x3);
> DPU_REG_WRITE(c, INTF_CONFIG, intf_cfg);
> DPU_REG_WRITE(c, INTF_PANEL_FORMAT, panel_format);
> + DPU_REG_WRITE(c, INTF_CONFIG2, intf_cfg2);
> + DPU_REG_WRITE(c, INTF_DISPLAY_DATA_HCTL, display_data_hctl);
> + DPU_REG_WRITE(c, INTF_ACTIVE_DATA_HCTL, active_data_hctl);
Which generations received these registers? I'd be more comfortable if
the driver didn't write into the registers that are not handled by the
hardware. The rest of DPU driver does exactly that.
Could you please add a check in the beginning of this function to print
and error message if wide bus is enabled, but DPU_DATA_HCTL_EN is not
supported. And move these writes under features check.
> }
>
> static void dpu_hw_intf_enable_timing_engine(
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.h b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.h
> index 3568be8..e4a518a 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.h
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.h
> @@ -30,6 +30,8 @@ struct intf_timing_params {
> u32 border_clr;
> u32 underflow_clr;
> u32 hsync_skew;
> +
> + bool wide_bus_en;
> };
>
> struct intf_prog_fetch {
--
With best wishes
Dmitry
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