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Date: Sat, 5 Feb 2022 01:05:43 +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 v3 1/3] drm/msm/dp: revise timing engine programming to
support widebus feature
On 04/02/2022 21:36, 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.
> In addition, revised timing engine function is an generic function and
> intend to be shared by all platforms to reduce maintenance efforts.
>
> 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
>
> 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 | 99 ++++++++++++++--------
> drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.h | 2 +
> 5 files changed, 93 insertions(+), 34 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> index 0d315b4..0c22839 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 99a5d73..893d74d 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_frame_count(struct drm_encoder *drm_enc);
>
> +bool dpu_encoder_is_widebus_enabled(struct drm_encoder *drm_enc);
> +
> #endif /* __DPU_ENCODER_H__ */
This chunk does not apply against the msm-next. The conflict is trivial,
but it would be nice to know that the code was tested against the
current tip.
> 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 185379b..3d6c914 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 (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..35d4aaa 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
> @@ -90,68 +91,95 @@ 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 +
> p->v_front_porch;
>
> display_v_start = ((p->vsync_pulse_width + p->v_back_porch) *
> - hsync_period) + p->hsync_skew;
> + hsync_period) + p->hsync_skew;
> display_v_end = ((vsync_period - p->v_front_porch) * hsync_period) +
> - p->hsync_skew - 1;
> + p->hsync_skew - 1;
> +
> + hsync_ctl = (hsync_period << 16) | p->hsync_pulse_width;
>
> 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) {
> - active_h_start = hsync_start_x;
> - active_h_end = active_h_start + p->xres - 1;
> - } else {
> - active_h_start = 0;
> - active_h_end = 0;
> - }
> + /*
> + * 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(4);
>
> - if (p->height != p->yres) {
> - active_v_start = display_v_start;
> - active_v_end = active_v_start + (p->yres * hsync_period) - 1;
> - } else {
> - active_v_start = 0;
> - active_v_end = 0;
> - }
> + if (p->wide_bus_en)
> + intf_cfg2 |= BIT(0);
>
> - if (active_h_end) {
> - active_hctl = (active_h_end << 16) | active_h_start;
> - intf_cfg |= BIT(29); /* ACTIVE_H_ENABLE */
> - } else {
> - active_hctl = 0;
> - }
> + /*
> + * If widebus is disabled:
> + * For uncompressed stream, the data is valid for the entire active
> + * window period.
> + * For compressed stream, data is valid for a shorter time period
> + * inside the active window depending on the compression ratio.
> + *
> + * If widebus is enabled:
> + * For uncompressed stream, data is valid for only half the active
> + * window, since the data rate is doubled in this mode.
> + * p->width holds the adjusted width for DP but unadjusted width for DSI
> + * For compressed stream, data validity window needs to be adjusted for
> + * compression ratio and then further halved.
> + */
> + data_width = p->width;
This assignment is rewritten in the next few lines! Please drop it, it's
unused.
> +
> + if (!dp_intf && p->wide_bus_en)
This condition does not make sense. wide_bus_en can only be enabled for
dp_intf, can it not? So the condition is always false.
> + data_width = p->width >> 1;
> + else
> + data_width = p->width;
>
> - if (active_v_end)
> - intf_cfg |= BIT(30); /* ACTIVE_V_ENABLE */
> + hsync_data_start_x = hsync_start_x;
> + hsync_data_end_x = hsync_start_x + data_width - 1;
>
> - hsync_ctl = (hsync_period << 16) | p->hsync_pulse_width;
> display_hctl = (hsync_end_x << 16) | hsync_start_x;
> + display_data_hctl = (hsync_data_end_x << 16) | hsync_data_start_x;
>
> - if (ctx->cap->type == INTF_EDP || ctx->cap->type == INTF_DP) {
> - 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;
> -
> + if (dp_intf) {
> + // DP timing adjustment
This is the only place with the C99 comment. Please use the surrounding
syntax.
> display_v_start += p->hsync_pulse_width + p->h_back_porch;
> + display_v_end -= p->h_front_porch;
> + }
> +
> + 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;
These assignments were only applied for the DP/eDP case. Could you
please elaborate the change? Why are you enabling them for the DSI and
HDMI outputs?
>
> - active_hctl = (active_h_end << 16) | active_h_start;
> + intf_cfg |= BIT(29); /* ACTIVE_H_ENABLE */
> + intf_cfg |= BIT(30); /* ACTIVE_V_ENABLE */
These were enabled only when active_h_end / active_v_end were non-zero.
Any comments?
> +
> + active_hctl = (active_h_end << 16) | active_h_start;
> +
> + if (dp_intf)
> display_hctl = active_hctl;
> - }
>
> den_polarity = 0;
> if (ctx->cap->type == INTF_HDMI) {
> @@ -204,6 +232,9 @@ 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);
I see. These writes are currently under the if (ctx->cap->features &
BIT(DPU_DATA_HCTL_EN)) condition. Please leave them there unless the
condition is wrong.
> }
>
> 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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