[PATCH 1/3] drm: atmel-hlcdc: add support for LVDS encoder type

[PATCH 1/3] drm: atmel-hlcdc: add support for LVDS encoder type

[Manikandan Muralidharan]

From: Dharma Balasubiramani <dharma.b@microchip.com>

Add support for encoder type "DRM_MODE_ENCODER_LVDS" with the following
bus formats:
	- RGB888_1X7X4_SPWG
	- RGB888_1X7X4_JEIDA
	- RGB666_1X7X3_SPWG
	- RGB666_1X18

Signed-off-by: Dharma Balasubiramani <dharma.b@microchip.com>
[manikandan.m@microchip.com: move modifications inside the
atmel_xlcdc_connector_output_lvds fn]
Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>
---
 .../gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c    | 38 +++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
index 0f7ffb3ced20..0e709047369a 100644
--- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
+++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
@@ -356,6 +356,42 @@ static int atmel_xlcdc_connector_output_dsi(struct drm_encoder *encoder,
 	return supported_fmts;
 }
 
+static int atmel_xlcdc_connector_output_lvds(struct drm_encoder *encoder,
+					     struct drm_display_info *info)
+{
+	int j;
+	unsigned int supported_fmts = 0;
+
+	switch (atmel_hlcdc_encoder_get_bus_fmt(encoder)) {
+	case 0:
+		break;
+	case MEDIA_BUS_FMT_RGB666_1X7X3_SPWG:
+	case MEDIA_BUS_FMT_RGB666_1X18:
+		return ATMEL_HLCDC_RGB666_OUTPUT;
+	case MEDIA_BUS_FMT_RGB888_1X7X4_SPWG:
+	case MEDIA_BUS_FMT_RGB888_1X7X4_JEIDA:
+		return ATMEL_HLCDC_RGB888_OUTPUT;
+	default:
+		return -EINVAL;
+	}
+
+	for (j = 0; j < info->num_bus_formats; j++) {
+		switch (info->bus_formats[j]) {
+		case MEDIA_BUS_FMT_RGB666_1X7X3_SPWG:
+		case MEDIA_BUS_FMT_RGB666_1X18:
+			supported_fmts |= ATMEL_HLCDC_RGB666_OUTPUT;
+			break;
+		case MEDIA_BUS_FMT_RGB888_1X7X4_SPWG:
+		case MEDIA_BUS_FMT_RGB888_1X7X4_JEIDA:
+			supported_fmts |= ATMEL_HLCDC_RGB888_OUTPUT;
+			break;
+		default:
+			break;
+		}
+	}
+	return supported_fmts;
+}
+
 static int atmel_hlcdc_connector_output_mode(struct drm_connector_state *state)
 {
 	struct drm_connector *connector = state->connector;
@@ -374,6 +410,8 @@ static int atmel_hlcdc_connector_output_mode(struct drm_connector_state *state)
 	 */
 	if (encoder->encoder_type == DRM_MODE_ENCODER_DSI)
 		return atmel_xlcdc_connector_output_dsi(encoder, info);
+	else if (encoder->encoder_type == DRM_MODE_ENCODER_LVDS)
+		return atmel_xlcdc_connector_output_lvds(encoder, info);
 
 	switch (atmel_hlcdc_encoder_get_bus_fmt(encoder)) {
 	case 0:
-- 
2.25.1

[PATCH 2/3] mfd: atmel-hlcdc: fetch LVDS PLL clock for LVDS display

[Manikandan Muralidharan]

The XLCDC IP supports DSI, parallel RGB and LVDS Display.
sys_clk(Generic clock) is used for DSI and Parallel RGB displays;
And LVDS PLL is used with LVDS displays.
obtain anyone of the clocks for the LCD to operate

Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>
Signed-off-by: Dharma Balasubiramani <dharma.b@microchip.com>
---
 drivers/mfd/atmel-hlcdc.c       | 16 ++++++++++++++--
 include/linux/mfd/atmel-hlcdc.h |  1 +
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/mfd/atmel-hlcdc.c b/drivers/mfd/atmel-hlcdc.c
index 4c4e35d404f3..60b0b766459e 100644
--- a/drivers/mfd/atmel-hlcdc.c
+++ b/drivers/mfd/atmel-hlcdc.c
@@ -108,10 +108,22 @@ static int atmel_hlcdc_probe(struct platform_device *pdev)
 		return PTR_ERR(hlcdc->periph_clk);
 	}
 
+	/*
+	 * Obtain one of the main clocks (GCK / LVDS PLL) required by the
+	 * LCD to function,
+	 * GCK for Parallel RGB and MIPI displays;
+	 * LVDS PLL for LVDS displays.
+	 */
+	hlcdc->sys_clk = NULL;
+	hlcdc->lvds_pll_clk = NULL;
 	hlcdc->sys_clk = devm_clk_get(dev, "sys_clk");
 	if (IS_ERR(hlcdc->sys_clk)) {
-		dev_err(dev, "failed to get system clock\n");
-		return PTR_ERR(hlcdc->sys_clk);
+		dev_dbg(dev, "failed to get system clock\n");
+		hlcdc->lvds_pll_clk = devm_clk_get(dev, "lvds_pll_clk");
+		if (IS_ERR(hlcdc->lvds_pll_clk)) {
+			dev_err(dev, "failed to get LVDS PLL clock\n");
+			return PTR_ERR(hlcdc->lvds_pll_clk);
+		}
 	}
 
 	hlcdc->slow_clk = devm_clk_get(dev, "slow_clk");
diff --git a/include/linux/mfd/atmel-hlcdc.h b/include/linux/mfd/atmel-hlcdc.h
index 80d675a03b39..07c2081867fd 100644
--- a/include/linux/mfd/atmel-hlcdc.h
+++ b/include/linux/mfd/atmel-hlcdc.h
@@ -75,6 +75,7 @@
  */
 struct atmel_hlcdc {
 	struct regmap *regmap;
+	struct clk *lvds_pll_clk;
 	struct clk *periph_clk;
 	struct clk *sys_clk;
 	struct clk *slow_clk;
-- 
2.25.1

[PATCH 3/3] drm: atmel-hlcdc: set LVDS PLL clock rate for LVDS Displays

[Manikandan Muralidharan]

From: Dharma Balasubiramani <dharma.b@microchip.com>

The LVDS PLL clock is 7x the Panel Pixel clock.
When using LVDS displays, the LVDS PLL clock rate is set using the
panel pixel clock, this skips the usage of 'assigned-clock-rates'
DT property for lvds_pll_clk clock for LCD node.

Signed-off-by: Dharma Balasubiramani <dharma.b@microchip.com>
Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>
---
 .../gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c    | 48 ++++++++++++++++---
 1 file changed, 42 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
index 0e709047369a..d11040d5cc5f 100644
--- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
+++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
@@ -99,9 +99,15 @@ static void atmel_hlcdc_crtc_mode_set_nofb(struct drm_crtc *c)
 		drm_connector_list_iter_end(&iter);
 	}
 
-	ret = clk_prepare_enable(crtc->dc->hlcdc->sys_clk);
-	if (ret)
-		return;
+	if (crtc->dc->hlcdc->lvds_pll_clk) {
+		ret = clk_prepare_enable(crtc->dc->hlcdc->lvds_pll_clk);
+		if (ret)
+			return;
+	} else {
+		ret = clk_prepare_enable(crtc->dc->hlcdc->sys_clk);
+		if (ret)
+			return;
+	}
 
 	vm.vfront_porch = adj->crtc_vsync_start - adj->crtc_vdisplay;
 	vm.vback_porch = adj->crtc_vtotal - adj->crtc_vsync_end;
@@ -186,7 +192,10 @@ static void atmel_hlcdc_crtc_mode_set_nofb(struct drm_crtc *c)
 			   ATMEL_XLCDC_DPI : ATMEL_HLCDC_MODE_MASK),
 			   cfg);
 
-	clk_disable_unprepare(crtc->dc->hlcdc->sys_clk);
+	if (crtc->dc->hlcdc->lvds_pll_clk)
+		clk_disable_unprepare(crtc->dc->hlcdc->lvds_pll_clk);
+	else
+		clk_disable_unprepare(crtc->dc->hlcdc->sys_clk);
 }
 
 static enum drm_mode_status
@@ -242,7 +251,11 @@ static void atmel_hlcdc_crtc_atomic_disable(struct drm_crtc *c,
 				    10, 1000))
 		dev_warn(dev->dev, "Atmel LCDC status register CLKSTS timeout\n");
 
-	clk_disable_unprepare(crtc->dc->hlcdc->sys_clk);
+	if (crtc->dc->hlcdc->lvds_pll_clk)
+		clk_disable_unprepare(crtc->dc->hlcdc->lvds_pll_clk);
+	else
+		clk_disable_unprepare(crtc->dc->hlcdc->sys_clk);
+
 	pinctrl_pm_select_sleep_state(dev->dev);
 
 	pm_runtime_allow(dev->dev);
@@ -255,15 +268,38 @@ static void atmel_hlcdc_crtc_atomic_enable(struct drm_crtc *c,
 {
 	struct drm_device *dev = c->dev;
 	struct atmel_hlcdc_crtc *crtc = drm_crtc_to_atmel_hlcdc_crtc(c);
+	struct drm_display_mode *adj = &c->state->adjusted_mode;
 	struct regmap *regmap = crtc->dc->hlcdc->regmap;
 	unsigned int status;
+	int ret;
 
 	pm_runtime_get_sync(dev->dev);
 
 	pm_runtime_forbid(dev->dev);
 
 	pinctrl_pm_select_default_state(dev->dev);
-	clk_prepare_enable(crtc->dc->hlcdc->sys_clk);
+
+	if (crtc->dc->hlcdc->lvds_pll_clk) {
+		/*
+		 * When using LVDS displays, fetch the pixel clock from the panel
+		 * and set the LVDS PLL clock rate.
+		 * As per the datasheet, LVDS PLL clock is 7x the pixel clock.
+		 */
+		ret = clk_set_rate(crtc->dc->hlcdc->lvds_pll_clk,
+				   (adj->clock * 7 * 1000));
+		if (ret) {
+			dev_err(dev->dev, "Failed to set LVDS PLL clk rate: %d\n", ret);
+			return;
+		}
+
+		ret = clk_prepare_enable(crtc->dc->hlcdc->lvds_pll_clk);
+		if (ret)
+			return;
+	} else {
+		ret = clk_prepare_enable(crtc->dc->hlcdc->sys_clk);
+		if (ret)
+			return;
+	}
 
 	regmap_write(regmap, ATMEL_HLCDC_EN, ATMEL_HLCDC_PIXEL_CLK);
 	if (regmap_read_poll_timeout(regmap, ATMEL_HLCDC_SR, status,
-- 
2.25.1

Re: [PATCH 2/3] mfd: atmel-hlcdc: fetch LVDS PLL clock for LVDS display

[Lee Jones]

On Thu, 21 Nov 2024, Manikandan Muralidharan wrote:

> The XLCDC IP supports DSI, parallel RGB and LVDS Display.
> sys_clk(Generic clock) is used for DSI and Parallel RGB displays;
> And LVDS PLL is used with LVDS displays.
> obtain anyone of the clocks for the LCD to operate

Maybe say something about this being a fall-back strategy.

> 
> Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>
> Signed-off-by: Dharma Balasubiramani <dharma.b@microchip.com>
> ---
>  drivers/mfd/atmel-hlcdc.c       | 16 ++++++++++++++--
>  include/linux/mfd/atmel-hlcdc.h |  1 +
>  2 files changed, 15 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mfd/atmel-hlcdc.c b/drivers/mfd/atmel-hlcdc.c
> index 4c4e35d404f3..60b0b766459e 100644
> --- a/drivers/mfd/atmel-hlcdc.c
> +++ b/drivers/mfd/atmel-hlcdc.c
> @@ -108,10 +108,22 @@ static int atmel_hlcdc_probe(struct platform_device *pdev)
>  		return PTR_ERR(hlcdc->periph_clk);
>  	}
>  
> +	/*
> +	 * Obtain one of the main clocks (GCK / LVDS PLL) required by the
> +	 * LCD to function,
> +	 * GCK for Parallel RGB and MIPI displays;
> +	 * LVDS PLL for LVDS displays.
> +	 */
> +	hlcdc->sys_clk = NULL;
> +	hlcdc->lvds_pll_clk = NULL;

Since, devm_kzalloc() is used to allocate this memory space, these are
already NULL.

>  	hlcdc->sys_clk = devm_clk_get(dev, "sys_clk");
>  	if (IS_ERR(hlcdc->sys_clk)) {
> -		dev_err(dev, "failed to get system clock\n");
> -		return PTR_ERR(hlcdc->sys_clk);
> +		dev_dbg(dev, "failed to get system clock\n");

This should be a dev_warn().

May be add some more information.

"failed to get system clock, trying xyz instead"

'\n' here.

> +		hlcdc->lvds_pll_clk = devm_clk_get(dev, "lvds_pll_clk");
> +		if (IS_ERR(hlcdc->lvds_pll_clk)) {
> +			dev_err(dev, "failed to get LVDS PLL clock\n");
> +			return PTR_ERR(hlcdc->lvds_pll_clk);
> +		}
>  	}
>  
>  	hlcdc->slow_clk = devm_clk_get(dev, "slow_clk");
> diff --git a/include/linux/mfd/atmel-hlcdc.h b/include/linux/mfd/atmel-hlcdc.h
> index 80d675a03b39..07c2081867fd 100644
> --- a/include/linux/mfd/atmel-hlcdc.h
> +++ b/include/linux/mfd/atmel-hlcdc.h
> @@ -75,6 +75,7 @@
>   */
>  struct atmel_hlcdc {
>  	struct regmap *regmap;
> +	struct clk *lvds_pll_clk;
>  	struct clk *periph_clk;
>  	struct clk *sys_clk;
>  	struct clk *slow_clk;
> -- 
> 2.25.1
> 

-- 
Lee Jones [李琼斯]