Re: [PATCH 1/4] drm/mgag200: Only set VIDRST bits in CRTC modesetting

[Jocelyn Falempe <jfalempe@xxxxxxxxxx>]

On 03/07/2024 15:40, Thomas Zimmermann wrote:
> The VRSTEN and HRSTEN bits control whether a CRTC synchronizes its
> display signal with an external source on the VIDRST pin. The G200WB
> and G200EW3 models synchronize with a BMC chip, but different external
> video encoders, such as the Matrox Maven, can also be attached to the
> pin.

If I understand correctly, it's a kind of VSYNC with the BMC, to avoid
tearing when using the remote console ?

> Only set VRSTEN and HRSTEN bits in the CRTC mode-setting code, so the
> driver maintains the bits independently from the BMC. Add the field
> set_vidrst to the CRTC state for this purpose. Off by default, control
> the CRTC VIDRST setting from the BMC's atomic_check helper. So if a
> BMC (or another external clock) requires synchronization, it instructs
> the CRTC to synchronize. >
> Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
> ---
>   drivers/gpu/drm/mgag200/mgag200_bmc.c    | 26 +++++++++++++++++++-----
>   drivers/gpu/drm/mgag200/mgag200_drv.h    |  5 ++++-
>   drivers/gpu/drm/mgag200/mgag200_g200er.c |  2 +-
>   drivers/gpu/drm/mgag200/mgag200_g200ev.c |  2 +-
>   drivers/gpu/drm/mgag200/mgag200_g200se.c |  2 +-
>   drivers/gpu/drm/mgag200/mgag200_mode.c   | 11 ++++++----
>   6 files changed, 35 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/mgag200/mgag200_bmc.c b/drivers/gpu/drm/mgag200/mgag200_bmc.c
> index 23ef85aa7e37..cb5400333862 100644
> --- a/drivers/gpu/drm/mgag200/mgag200_bmc.c
> +++ b/drivers/gpu/drm/mgag200/mgag200_bmc.c
> @@ -77,11 +77,6 @@ void mgag200_bmc_enable_vidrst(struct mga_device *mdev)
>   {
>   	u8 tmp;
>   
> -	/* Ensure that the vrsten and hrsten are set */
> -	WREG8(MGAREG_CRTCEXT_INDEX, 1);
> -	tmp = RREG8(MGAREG_CRTCEXT_DATA);
> -	WREG8(MGAREG_CRTCEXT_DATA, tmp | 0x88);
> -
>   	/* Assert rstlvl2 */
>   	WREG8(DAC_INDEX, MGA1064_REMHEADCTL2);
>   	tmp = RREG8(DAC_DATA);
> @@ -108,6 +103,25 @@ void mgag200_bmc_enable_vidrst(struct mga_device *mdev)
>   	WREG_DAC(MGA1064_GEN_IO_DATA, tmp);
>   }
>   
> +static int mgag200_bmc_encoder_helper_atomic_check(struct drm_encoder *encoder,
> +						   struct drm_crtc_state *crtc_state,
> +						   struct drm_connector_state *conn_state)
> +{
> +	struct mga_device *mdev = to_mga_device(encoder->dev);
> +	struct mgag200_crtc_state *mgag200_crtc_state = to_mgag200_crtc_state(crtc_state);
> +
> +	if (mdev->info->has_vidrst)
> +		mgag200_crtc_state->set_vidrst = true;
> +	else
> +		mgag200_crtc_state->set_vidrst = false;
> +

I think you can simplify it with:

mgag200_crtc_state->set_vidrst = mdev->info->has_vidrst;

> +	return 0;
> +}
> +
> +static const struct drm_encoder_helper_funcs mgag200_bmc_encoder_helper_funcs = {
> +	.atomic_check = mgag200_bmc_encoder_helper_atomic_check,
> +};
> +
>   static const struct drm_encoder_funcs mgag200_bmc_encoder_funcs = {
>   	.destroy = drm_encoder_cleanup,
>   };
> @@ -190,6 +204,8 @@ int mgag200_bmc_output_init(struct mga_device *mdev, struct drm_connector *physi
>   			       DRM_MODE_ENCODER_VIRTUAL, NULL);
>   	if (ret)
>   		return ret;
> +	drm_encoder_helper_add(encoder, &mgag200_bmc_encoder_helper_funcs);
> +
>   	encoder->possible_crtcs = drm_crtc_mask(crtc);
>   
>   	bmc_connector = &mdev->output.bmc.bmc_connector;
> diff --git a/drivers/gpu/drm/mgag200/mgag200_drv.h b/drivers/gpu/drm/mgag200/mgag200_drv.h
> index 7f7dfbd0f013..4b75613de882 100644
> --- a/drivers/gpu/drm/mgag200/mgag200_drv.h
> +++ b/drivers/gpu/drm/mgag200/mgag200_drv.h
> @@ -179,6 +179,8 @@ struct mgag200_crtc_state {
>   	const struct drm_format_info *format;
>   
>   	struct mgag200_pll_values pixpllc;
> +
> +	bool set_vidrst;
>   };
>   
>   static inline struct mgag200_crtc_state *to_mgag200_crtc_state(struct drm_crtc_state *base)
> @@ -430,7 +432,8 @@ void mgag200_crtc_atomic_destroy_state(struct drm_crtc *crtc, struct drm_crtc_st
>   	.atomic_duplicate_state = mgag200_crtc_atomic_duplicate_state, \
>   	.atomic_destroy_state = mgag200_crtc_atomic_destroy_state
>   
> -void mgag200_set_mode_regs(struct mga_device *mdev, const struct drm_display_mode *mode);
> +void mgag200_set_mode_regs(struct mga_device *mdev, const struct drm_display_mode *mode,
> +			   bool set_vidrst);
>   void mgag200_set_format_regs(struct mga_device *mdev, const struct drm_format_info *format);
>   void mgag200_enable_display(struct mga_device *mdev);
>   void mgag200_init_registers(struct mga_device *mdev);
> diff --git a/drivers/gpu/drm/mgag200/mgag200_g200er.c b/drivers/gpu/drm/mgag200/mgag200_g200er.c
> index 4e8a1756138d..abfbed6ec390 100644
> --- a/drivers/gpu/drm/mgag200/mgag200_g200er.c
> +++ b/drivers/gpu/drm/mgag200/mgag200_g200er.c
> @@ -195,7 +195,7 @@ static void mgag200_g200er_crtc_helper_atomic_enable(struct drm_crtc *crtc,
>   		funcs->disable_vidrst(mdev);
>   
>   	mgag200_set_format_regs(mdev, format);
> -	mgag200_set_mode_regs(mdev, adjusted_mode);
> +	mgag200_set_mode_regs(mdev, adjusted_mode, mgag200_crtc_state->set_vidrst);
>   
>   	if (funcs->pixpllc_atomic_update)
>   		funcs->pixpllc_atomic_update(crtc, old_state);
> diff --git a/drivers/gpu/drm/mgag200/mgag200_g200ev.c b/drivers/gpu/drm/mgag200/mgag200_g200ev.c
> index d884f3cb0ec7..acc99999e2b5 100644
> --- a/drivers/gpu/drm/mgag200/mgag200_g200ev.c
> +++ b/drivers/gpu/drm/mgag200/mgag200_g200ev.c
> @@ -196,7 +196,7 @@ static void mgag200_g200ev_crtc_helper_atomic_enable(struct drm_crtc *crtc,
>   		funcs->disable_vidrst(mdev);
>   
>   	mgag200_set_format_regs(mdev, format);
> -	mgag200_set_mode_regs(mdev, adjusted_mode);
> +	mgag200_set_mode_regs(mdev, adjusted_mode, mgag200_crtc_state->set_vidrst);
>   
>   	if (funcs->pixpllc_atomic_update)
>   		funcs->pixpllc_atomic_update(crtc, old_state);
> diff --git a/drivers/gpu/drm/mgag200/mgag200_g200se.c b/drivers/gpu/drm/mgag200/mgag200_g200se.c
> index a824bb8ad579..be4e124102c6 100644
> --- a/drivers/gpu/drm/mgag200/mgag200_g200se.c
> +++ b/drivers/gpu/drm/mgag200/mgag200_g200se.c
> @@ -327,7 +327,7 @@ static void mgag200_g200se_crtc_helper_atomic_enable(struct drm_crtc *crtc,
>   		funcs->disable_vidrst(mdev);
>   
>   	mgag200_set_format_regs(mdev, format);
> -	mgag200_set_mode_regs(mdev, adjusted_mode);
> +	mgag200_set_mode_regs(mdev, adjusted_mode, mgag200_crtc_state->set_vidrst);
>   
>   	if (funcs->pixpllc_atomic_update)
>   		funcs->pixpllc_atomic_update(crtc, old_state);
> diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c
> index bb6204002cb3..4f4612192e30 100644
> --- a/drivers/gpu/drm/mgag200/mgag200_mode.c
> +++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
> @@ -201,9 +201,9 @@ void mgag200_init_registers(struct mga_device *mdev)
>   	WREG8(MGA_MISC_OUT, misc);
>   }
>   
> -void mgag200_set_mode_regs(struct mga_device *mdev, const struct drm_display_mode *mode)
> +void mgag200_set_mode_regs(struct mga_device *mdev, const struct drm_display_mode *mode,
> +			   bool set_vidrst)
>   {
> -	const struct mgag200_device_info *info = mdev->info;
>   	unsigned int hdisplay, hsyncstart, hsyncend, htotal;
>   	unsigned int vdisplay, vsyncstart, vsyncend, vtotal;
>   	u8 misc, crtcext1, crtcext2, crtcext5;
> @@ -238,9 +238,11 @@ void mgag200_set_mode_regs(struct mga_device *mdev, const struct drm_display_mod
>   		   ((hdisplay & 0x100) >> 7) |
>   		   ((hsyncstart & 0x100) >> 6) |
>   		    (htotal & 0x40);
> -	if (info->has_vidrst)
> +	if (set_vidrst)
>   		crtcext1 |= MGAREG_CRTCEXT1_VRSTEN |
>   			    MGAREG_CRTCEXT1_HRSTEN;
> +	else
> +		crtcext1 &= ~(MGAREG_CRTCEXT1_VRSTEN | MGAREG_CRTCEXT1_HRSTEN);
>   
>   	crtcext2 = ((vtotal & 0xc00) >> 10) |
>   		   ((vdisplay & 0x400) >> 8) |
> @@ -656,7 +658,7 @@ void mgag200_crtc_helper_atomic_enable(struct drm_crtc *crtc, struct drm_atomic_
>   		funcs->disable_vidrst(mdev);
>   
>   	mgag200_set_format_regs(mdev, format);
> -	mgag200_set_mode_regs(mdev, adjusted_mode);
> +	mgag200_set_mode_regs(mdev, adjusted_mode, mgag200_crtc_state->set_vidrst);
>   
>   	if (funcs->pixpllc_atomic_update)
>   		funcs->pixpllc_atomic_update(crtc, old_state);
> @@ -717,6 +719,7 @@ struct drm_crtc_state *mgag200_crtc_atomic_duplicate_state(struct drm_crtc *crtc
>   	new_mgag200_crtc_state->format = mgag200_crtc_state->format;
>   	memcpy(&new_mgag200_crtc_state->pixpllc, &mgag200_crtc_state->pixpllc,
>   	       sizeof(new_mgag200_crtc_state->pixpllc));
> +	new_mgag200_crtc_state->set_vidrst = mgag200_crtc_state->set_vidrst;
>   
>   	return &new_mgag200_crtc_state->base;
>   }

With the small nitpick.

Reviewed-by: Jocelyn Falempe <jfalempe@xxxxxxxxxx>


--

Jocelyn