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Message-ID: <CAA8EJprnUuO2yd4FcPtmfcMwAmZqR3GyFJ+Cz-KV8E4O6c8R6w@mail.gmail.com>
Date: Wed, 16 Feb 2022 20:48:26 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Kuogee Hsieh <quic_khsieh@...cinc.com>
Cc: 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, 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 v6 1/2] drm/msm/dpu: revise timing engine programming to
support widebus feature
On Wed, 16 Feb 2022 at 20:34, Kuogee Hsieh <quic_khsieh@...cinc.com> 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
>
> Signed-off-by: Kuogee Hsieh <quic_khsieh@...cinc.com>
> ---
> 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 | 63 ++++++++++++++++------
> drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.h | 2 +
> 5 files changed, 76 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..303bd03 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
> @@ -60,6 +61,14 @@
>
> #define INTF_MUX 0x25C
>
> +#define INTF_CFG_ACTIVE_H_EN BIT(29)
> +#define INTF_CFG_ACTIVE_V_EN BIT(30)
> +
> +#define INTF_CFG2_DATABUS_WIDEN BIT(0)
> +#define INTF_CFG2_DATA_HCTL_EN BIT(4)
> +#define INTF_CFG2_DCE_DATA_COMPRESS BIT(12)
> +
> +
> static const struct dpu_intf_cfg *_intf_offset(enum dpu_intf intf,
> const struct dpu_mdss_cfg *m,
> void __iomem *addr,
> @@ -90,15 +99,23 @@ 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 +129,7 @@ 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 +137,7 @@ 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 +147,47 @@ 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 |= INTF_CFG_ACTIVE_H_EN;
> } else {
> active_hctl = 0;
> }
>
> if (active_v_end)
> - intf_cfg |= BIT(30); /* ACTIVE_V_ENABLE */
> + intf_cfg |= INTF_CFG_ACTIVE_V_EN;
Quoting v4:
Such changes can go to a separate patch. You don't have to squash
everything in a single patch. Quite the opposite. If each of the
patches is atomic, it's easier to review and accept them.
>
> 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 |= (INTF_CFG2_DATABUS_WIDEN | INTF_CFG2_DATA_HCTL_EN);
> +
> + 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 |= INTF_CFG_ACTIVE_H_EN;
> + intf_cfg |= INTF_CFG_ACTIVE_V_EN;
> }
>
> den_polarity = 0;
> @@ -180,13 +217,6 @@ 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)) {
Quoting a quesiton to v4:
So, we are enabling it uncoditionally even for older platforms, which
do not support this bit/register. I'm not a fan of writing to
registers which are not supported by the hardware.
Another:
If you insist on always programming these registers, the
DPU_DATA_HCTL_EN becomes useless and should be removed from the
dpu_hw_catalog. As usual, in a separate patch.
> - 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 +234,9 @@ 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);
> }
>
> 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 {
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>
--
With best wishes
Dmitry
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