drm: mali-dp: Check the mclk rate and allow up/down scaling

When downscaling, mclk needs to be sufficiently higher than pxlclk in
order to be able to fetch the higher-resolution data and produce output
pixels. When not scaling, or when upscaling, mclk can be equal to
pxlclk. Since the driver doesn't control mclk, just ensure that the
requirement is satisfied with the current clock rate.

Signed-off-by: Mihail Atanassov <mihail.atanassov@arm.com>
Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>

1 files changed, 70 insertions, 0 deletions

diff --git a/drivers/gpu/drm/arm/malidp_hw.c b/drivers/gpu/drm/arm/malidp_hw.c
index e444c23a8261..28360b8542f7 100644
--- a/drivers/gpu/drm/arm/malidp_hw.c
+++ b/drivers/gpu/drm/arm/malidp_hw.c
@@ -12,6 +12,7 @@
  * in an attempt to provide to the rest of the driver code a unified view
  */
 
+#include <linux/clk.h>
 #include <linux/types.h>
 #include <linux/io.h>
 #include <drm/drmP.h>
@@ -334,6 +335,39 @@ static int malidp500_se_set_scaling_coeffs(struct malidp_hw_device *hwdev,
 	return 0;
 }
 
+static long malidp500_se_calc_mclk(struct malidp_hw_device *hwdev,
+				   struct malidp_se_config *se_config,
+				   struct videomode *vm)
+{
+	unsigned long mclk;
+	unsigned long pxlclk = vm->pixelclock; /* Hz */
+	unsigned long htotal = vm->hactive + vm->hfront_porch +
+			       vm->hback_porch + vm->hsync_len;
+	unsigned long input_size = se_config->input_w * se_config->input_h;
+	unsigned long a = 10;
+	long ret;
+
+	/*
+	 * mclk = max(a, 1.5) * pxlclk
+	 *
+	 * To avoid float calculaiton, using 15 instead of 1.5 and div by
+	 * 10 to get mclk.
+	 */
+	if (se_config->scale_enable) {
+		a = 15 * input_size / (htotal * se_config->output_h);
+		if (a < 15)
+			a = 15;
+	}
+	mclk = a * pxlclk / 10;
+	ret = clk_get_rate(hwdev->mclk);
+	if (ret < mclk) {
+		DRM_DEBUG_DRIVER("mclk requirement of %lu kHz can't be met.\n",
+				 mclk / 1000);
+		return -EINVAL;
+	}
+	return ret;
+}
+
 static int malidp550_query_hw(struct malidp_hw_device *hwdev)
 {
 	u32 conf = malidp_hw_read(hwdev, MALIDP550_CONFIG_ID);
@@ -521,6 +555,39 @@ static int malidp550_se_set_scaling_coeffs(struct malidp_hw_device *hwdev,
 	return 0;
 }
 
+static long malidp550_se_calc_mclk(struct malidp_hw_device *hwdev,
+				   struct malidp_se_config *se_config,
+				   struct videomode *vm)
+{
+	unsigned long mclk;
+	unsigned long pxlclk = vm->pixelclock;
+	unsigned long htotal = vm->hactive + vm->hfront_porch +
+			       vm->hback_porch + vm->hsync_len;
+	unsigned long numerator = 1, denominator = 1;
+	long ret;
+
+	if (se_config->scale_enable) {
+		numerator = max(se_config->input_w, se_config->output_w) *
+			    se_config->input_h;
+		numerator += se_config->output_w *
+			     (se_config->output_h -
+			      min(se_config->input_h, se_config->output_h));
+		denominator = (htotal - 2) * se_config->output_h;
+	}
+
+	/* mclk can't be slower than pxlclk. */
+	if (numerator < denominator)
+		numerator = denominator = 1;
+	mclk = (pxlclk * numerator) / denominator;
+	ret = clk_get_rate(hwdev->mclk);
+	if (ret < mclk) {
+		DRM_DEBUG_DRIVER("mclk requirement of %lu kHz can't be met.\n",
+				 mclk / 1000);
+		return -EINVAL;
+	}
+	return ret;
+}
+
 static int malidp650_query_hw(struct malidp_hw_device *hwdev)
 {
 	u32 conf = malidp_hw_read(hwdev, MALIDP550_CONFIG_ID);
@@ -586,6 +653,7 @@ const struct malidp_hw_device malidp_device[MALIDP_MAX_DEVICES] = {
 		.modeset = malidp500_modeset,
 		.rotmem_required = malidp500_rotmem_required,
 		.se_set_scaling_coeffs = malidp500_se_set_scaling_coeffs,
+		.se_calc_mclk = malidp500_se_calc_mclk,
 		.features = MALIDP_DEVICE_LV_HAS_3_STRIDES,
 	},
 	[MALIDP_550] = {
@@ -622,6 +690,7 @@ const struct malidp_hw_device malidp_device[MALIDP_MAX_DEVICES] = {
 		.modeset = malidp550_modeset,
 		.rotmem_required = malidp550_rotmem_required,
 		.se_set_scaling_coeffs = malidp550_se_set_scaling_coeffs,
+		.se_calc_mclk = malidp550_se_calc_mclk,
 		.features = 0,
 	},
 	[MALIDP_650] = {
@@ -659,6 +728,7 @@ const struct malidp_hw_device malidp_device[MALIDP_MAX_DEVICES] = {
 		.modeset = malidp550_modeset,
 		.rotmem_required = malidp550_rotmem_required,
 		.se_set_scaling_coeffs = malidp550_se_set_scaling_coeffs,
+		.se_calc_mclk = malidp550_se_calc_mclk,
 		.features = 0,
 	},
 };