drm: mxsfb: Add interconnect path request
diff mbox series

Message ID 20201201103757.32165-1-martin.kepplinger@puri.sm
State New, archived
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Series
  • drm: mxsfb: Add interconnect path request
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Commit Message

Martin Kepplinger Dec. 1, 2020, 10:37 a.m. UTC
Add interconnect support to mxsfb so that it is able to request enough
bandwidth to DDR for display output to work.

Signed-off-by: Martin Kepplinger <martin.kepplinger@puri.sm>
---
 drivers/gpu/drm/mxsfb/mxsfb_drv.c | 33 +++++++++++++++++++++++++++++++
 drivers/gpu/drm/mxsfb/mxsfb_drv.h |  2 ++
 drivers/gpu/drm/mxsfb/mxsfb_kms.c | 13 ++++++++++++
 3 files changed, 48 insertions(+)

Comments

Lucas Stach Dec. 1, 2020, 11:20 a.m. UTC | #1
Am Dienstag, den 01.12.2020, 11:37 +0100 schrieb Martin Kepplinger:
> Add interconnect support to mxsfb so that it is able to request enough
> bandwidth to DDR for display output to work.
> 
> Signed-off-by: Martin Kepplinger <martin.kepplinger@puri.sm>
> ---
>  drivers/gpu/drm/mxsfb/mxsfb_drv.c | 33 +++++++++++++++++++++++++++++++
>  drivers/gpu/drm/mxsfb/mxsfb_drv.h |  2 ++
>  drivers/gpu/drm/mxsfb/mxsfb_kms.c | 13 ++++++++++++
>  3 files changed, 48 insertions(+)
> 
> diff --git a/drivers/gpu/drm/mxsfb/mxsfb_drv.c b/drivers/gpu/drm/mxsfb/mxsfb_drv.c
> index 6faf17b6408d..b05e8e5f1e38 100644
> --- a/drivers/gpu/drm/mxsfb/mxsfb_drv.c
> +++ b/drivers/gpu/drm/mxsfb/mxsfb_drv.c
> @@ -15,6 +15,7 @@
>  #include <linux/of_device.h>
>  #include <linux/platform_device.h>
>  #include <linux/pm_runtime.h>
> +#include <linux/interconnect.h>
>  
> 
> 
> 
>  #include <drm/drm_atomic_helper.h>
>  #include <drm/drm_bridge.h>
> @@ -311,6 +312,34 @@ static const struct of_device_id mxsfb_dt_ids[] = {
>  };
>  MODULE_DEVICE_TABLE(of, mxsfb_dt_ids);
> 
> +
> +static int mxsfb_init_icc(struct platform_device *pdev)
> +{
> +	struct drm_device *drm = platform_get_drvdata(pdev);
> +	struct mxsfb_drm_private *mxsfb = drm->dev_private;
> +	int ret;
> +
> +	/* Optional interconnect request */
> +	mxsfb->icc_path = devm_of_icc_get(&pdev->dev, "lcdif-dram");
> +	if (IS_ERR(mxsfb->icc_path)) {
> +		ret = PTR_ERR(mxsfb->icc_path);
> +		if (ret == -EPROBE_DEFER)
> +			return ret;
> +
> +		mxsfb->icc_path = NULL;
> +		dev_dbg(drm->dev,
> +			"No interconnect may cause display underflows!\n");
> +	}
> +
> +	ret = icc_set_bw(mxsfb->icc_path, 0, MBps_to_icc(700));

Shouldn't this be proportional to the current mode, instead of a fixed
value? 700MB looks like 1080p@60Hz@32bpp with a bit of headroom, but
there are many valid use-cases where significantly smaller displays are
connected to the eLCDIF. Also it doesn't cover the case where an
overlay is active, which needs additional bandwidth.

> +	if (ret) {
> +		dev_err(drm->dev, "%s: icc_set_bw failed: %d\n", __func__, ret);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
[...]
>  #include <drm/drm_atomic.h>
>  #include <drm/drm_atomic_helper.h>
> @@ -310,6 +311,12 @@ static void mxsfb_crtc_atomic_enable(struct drm_crtc *crtc,
>  	struct mxsfb_drm_private *mxsfb = to_mxsfb_drm_private(crtc->dev);
>  	struct drm_device *drm = mxsfb->drm;
>  	dma_addr_t paddr;
> +	int ret;
> +
> +	ret = icc_enable(mxsfb->icc_path);
> +	if (ret)
> +		dev_err_ratelimited(drm->dev, "%s: icc_enable failed: %d\n",
> +				    __func__, ret);

Why ratelimited? I wouldn't expect atomic enable/disable to be called
often enough for this to make any difference.

Regards,
Lucas

> 
>  	pm_runtime_get_sync(drm->dev);
>  	mxsfb_enable_axi_clk(mxsfb);

Patch
diff mbox series

diff --git a/drivers/gpu/drm/mxsfb/mxsfb_drv.c b/drivers/gpu/drm/mxsfb/mxsfb_drv.c
index 6faf17b6408d..b05e8e5f1e38 100644
--- a/drivers/gpu/drm/mxsfb/mxsfb_drv.c
+++ b/drivers/gpu/drm/mxsfb/mxsfb_drv.c
@@ -15,6 +15,7 @@ 
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
+#include <linux/interconnect.h>
 
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_bridge.h>
@@ -311,6 +312,34 @@  static const struct of_device_id mxsfb_dt_ids[] = {
 };
 MODULE_DEVICE_TABLE(of, mxsfb_dt_ids);
 
+
+static int mxsfb_init_icc(struct platform_device *pdev)
+{
+	struct drm_device *drm = platform_get_drvdata(pdev);
+	struct mxsfb_drm_private *mxsfb = drm->dev_private;
+	int ret;
+
+	/* Optional interconnect request */
+	mxsfb->icc_path = devm_of_icc_get(&pdev->dev, "lcdif-dram");
+	if (IS_ERR(mxsfb->icc_path)) {
+		ret = PTR_ERR(mxsfb->icc_path);
+		if (ret == -EPROBE_DEFER)
+			return ret;
+
+		mxsfb->icc_path = NULL;
+		dev_dbg(drm->dev,
+			"No interconnect may cause display underflows!\n");
+	}
+
+	ret = icc_set_bw(mxsfb->icc_path, 0, MBps_to_icc(700));
+	if (ret) {
+		dev_err(drm->dev, "%s: icc_set_bw failed: %d\n", __func__, ret);
+		return ret;
+	}
+
+	return 0;
+}
+
 static int mxsfb_probe(struct platform_device *pdev)
 {
 	struct drm_device *drm;
@@ -329,6 +358,10 @@  static int mxsfb_probe(struct platform_device *pdev)
 	if (ret)
 		goto err_free;
 
+	ret = mxsfb_init_icc(pdev);
+	if (ret)
+		goto err_free;
+
 	ret = drm_dev_register(drm, 0);
 	if (ret)
 		goto err_unload;
diff --git a/drivers/gpu/drm/mxsfb/mxsfb_drv.h b/drivers/gpu/drm/mxsfb/mxsfb_drv.h
index 399d23e91ed1..d74ff4818e62 100644
--- a/drivers/gpu/drm/mxsfb/mxsfb_drv.h
+++ b/drivers/gpu/drm/mxsfb/mxsfb_drv.h
@@ -41,6 +41,8 @@  struct mxsfb_drm_private {
 	struct drm_encoder		encoder;
 	struct drm_connector		*connector;
 	struct drm_bridge		*bridge;
+
+	struct icc_path			*icc_path;
 };
 
 static inline struct mxsfb_drm_private *
diff --git a/drivers/gpu/drm/mxsfb/mxsfb_kms.c b/drivers/gpu/drm/mxsfb/mxsfb_kms.c
index 3e1bb0aefb87..8925ee7deeaa 100644
--- a/drivers/gpu/drm/mxsfb/mxsfb_kms.c
+++ b/drivers/gpu/drm/mxsfb/mxsfb_kms.c
@@ -13,6 +13,7 @@ 
 #include <linux/iopoll.h>
 #include <linux/pm_runtime.h>
 #include <linux/spinlock.h>
+#include <linux/interconnect.h>
 
 #include <drm/drm_atomic.h>
 #include <drm/drm_atomic_helper.h>
@@ -310,6 +311,12 @@  static void mxsfb_crtc_atomic_enable(struct drm_crtc *crtc,
 	struct mxsfb_drm_private *mxsfb = to_mxsfb_drm_private(crtc->dev);
 	struct drm_device *drm = mxsfb->drm;
 	dma_addr_t paddr;
+	int ret;
+
+	ret = icc_enable(mxsfb->icc_path);
+	if (ret)
+		dev_err_ratelimited(drm->dev, "%s: icc_enable failed: %d\n",
+				    __func__, ret);
 
 	pm_runtime_get_sync(drm->dev);
 	mxsfb_enable_axi_clk(mxsfb);
@@ -334,6 +341,7 @@  static void mxsfb_crtc_atomic_disable(struct drm_crtc *crtc,
 	struct mxsfb_drm_private *mxsfb = to_mxsfb_drm_private(crtc->dev);
 	struct drm_device *drm = mxsfb->drm;
 	struct drm_pending_vblank_event *event;
+	int ret;
 
 	mxsfb_disable_controller(mxsfb);
 
@@ -349,6 +357,11 @@  static void mxsfb_crtc_atomic_disable(struct drm_crtc *crtc,
 
 	mxsfb_disable_axi_clk(mxsfb);
 	pm_runtime_put_sync(drm->dev);
+
+	ret = icc_disable(mxsfb->icc_path);
+	if (ret)
+		dev_err_ratelimited(drm->dev, "%s: icc_disable failed: %d\n",
+				    __func__, ret);
 }
 
 static int mxsfb_crtc_enable_vblank(struct drm_crtc *crtc)