Re: [PATCH v3 5/8] drm/simpledrm: Add support for system memory framebuffers

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Hi

Am 17.11.22 um 19:40 schrieb Thierry Reding:
From: Thierry Reding <treding@xxxxxxxxxx>

Simple framebuffers can be set up in system memory, which cannot be
requested and/or I/O remapped using the I/O resource helpers. Add a
separate code path that obtains system memory framebuffers from the
reserved memory region referenced in the memory-region property.

Signed-off-by: Thierry Reding <treding@xxxxxxxxxx>
---
Changes in v3:
- simplify memory code and move back to simpledrm_device_create()
- extract screen_base iosys_map fix into separate patch

Changes in v2:
- make screen base a struct iosys_map to avoid sparse warnings

  drivers/gpu/drm/tiny/simpledrm.c | 99 ++++++++++++++++++++++++--------
  1 file changed, 75 insertions(+), 24 deletions(-)

diff --git a/drivers/gpu/drm/tiny/simpledrm.c b/drivers/gpu/drm/tiny/simpledrm.c
index 3673a42e4bf4..7f39bc58da52 100644
--- a/drivers/gpu/drm/tiny/simpledrm.c
+++ b/drivers/gpu/drm/tiny/simpledrm.c
@@ -3,6 +3,7 @@
  #include <linux/clk.h>
  #include <linux/of_clk.h>
  #include <linux/minmax.h>
+#include <linux/of_address.h>
  #include <linux/platform_data/simplefb.h>
  #include <linux/platform_device.h>
  #include <linux/regulator/consumer.h>
@@ -184,6 +185,31 @@ simplefb_get_format_of(struct drm_device *dev, struct device_node *of_node)
  	return simplefb_get_validated_format(dev, format);
  }
+static struct resource *
+simplefb_get_memory_of(struct drm_device *dev, struct device_node *of_node)
+{
+	struct device_node *np;
+	struct resource *res;
+	int err;
+
+	np = of_parse_phandle(of_node, "memory-region", 0);
+	if (!np)
+		return NULL;
+
+	res = devm_kzalloc(dev->dev, sizeof(*res), GFP_KERNEL);
+	if (!res)
+		return ERR_PTR(-ENOMEM);
+
+	err = of_address_to_resource(np, 0, res);
+	if (err)
+		return ERR_PTR(err);
+
+	if (of_get_property(of_node, "reg", NULL))
+		drm_warn(dev, "preferring \"memory-region\" over \"reg\" property\n");
+
+	return res;
+}
+
  /*
   * Simple Framebuffer device
   */
@@ -623,8 +649,7 @@ static struct simpledrm_device *simpledrm_device_create(struct drm_driver *drv,
  	struct drm_device *dev;
  	int width, height, stride;
  	const struct drm_format_info *format;
-	struct resource *res, *mem;
-	void __iomem *screen_base;
+	struct resource *res, *mem = NULL;
  	struct drm_plane *primary_plane;
  	struct drm_crtc *crtc;
  	struct drm_encoder *encoder;
@@ -676,6 +701,9 @@ static struct simpledrm_device *simpledrm_device_create(struct drm_driver *drv,
  		format = simplefb_get_format_of(dev, of_node);
  		if (IS_ERR(format))
  			return ERR_CAST(format);
+		mem = simplefb_get_memory_of(dev, of_node);
+		if (IS_ERR(mem))
+			return ERR_CAST(mem);
  	} else {
  		drm_err(dev, "no simplefb configuration found\n");
  		return ERR_PTR(-ENODEV);
@@ -698,32 +726,55 @@ static struct simpledrm_device *simpledrm_device_create(struct drm_driver *drv,
  	 * Memory management
  	 */
- res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	if (!res)
-		return ERR_PTR(-EINVAL);
+	if (mem) {
+		void *screen_base;
- ret = devm_aperture_acquire_from_firmware(dev, res->start, resource_size(res));
-	if (ret) {
-		drm_err(dev, "could not acquire memory range %pr: error %d\n", res, ret);
-		return ERR_PTR(ret);
-	}
+		ret = devm_aperture_acquire_from_firmware(dev, mem->start, resource_size(mem));
+		if (ret) {
+			drm_err(dev, "could not acquire memory range %pr: %d\n", mem, ret);
+			return ERR_PTR(ret);
+		}
- mem = devm_request_mem_region(&pdev->dev, res->start, resource_size(res), drv->name);
-	if (!mem) {
-		/*
-		 * We cannot make this fatal. Sometimes this comes from magic
-		 * spaces our resource handlers simply don't know about. Use
-		 * the I/O-memory resource as-is and try to map that instead.
-		 */
-		drm_warn(dev, "could not acquire memory region %pr\n", res);
-		mem = res;
-	}
+		drm_info(dev, "using system memory framebuffer at %pr\n", mem);

drm_dbg() please.

- screen_base = devm_ioremap_wc(&pdev->dev, mem->start, resource_size(mem));
-	if (!screen_base)
-		return ERR_PTR(-ENOMEM);
+		screen_base = devm_memremap(dev->dev, mem->start, resource_size(mem), MEMREMAP_WB);
+		if (!screen_base)
+			return ERR_PTR(-ENOMEM);
+
+		iosys_map_set_vaddr(&sdev->screen_base, screen_base);
+	} else {
+		void __iomem *screen_base;
+
+		res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+		if (!res)
+			return ERR_PTR(-EINVAL);
- iosys_map_set_vaddr_iomem(&sdev->screen_base, screen_base);
+		ret = devm_aperture_acquire_from_firmware(dev, res->start, resource_size(res));
+		if (ret) {
+			drm_err(dev, "could not acquire memory range %pr: %d\n", &res, ret);
+			return ERR_PTR(ret);
+		}
+
+		drm_info(dev, "using I/O memory framebuffer at %pr\n", res);

drm_dbg()

With the small fixes, please add

Reviewed-by: Thomas Zimmermann <tzimmermann@xxxxxxx>

Best regards
Thomas

+
+		mem = devm_request_mem_region(&pdev->dev, res->start, resource_size(res),
+					      drv->name);
+		if (!mem) {
+			/*
+			 * We cannot make this fatal. Sometimes this comes from magic
+			 * spaces our resource handlers simply don't know about. Use
+			 * the I/O-memory resource as-is and try to map that instead.
+			 */
+			drm_warn(dev, "could not acquire memory region %pr\n", res);
+			mem = res;
+		}
+
+		screen_base = devm_ioremap_wc(&pdev->dev, mem->start, resource_size(mem));
+		if (!screen_base)
+			return ERR_PTR(-ENOMEM);
+
+		iosys_map_set_vaddr_iomem(&sdev->screen_base, screen_base);
+	}
/*
  	 * Modesetting

--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev

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