On 24/01/2022 13:36, Thomas Zimmermann wrote:
Requesting the framebuffer memory in simpledrm marks the memory
range as busy. This used to be done by the firmware sysfb code,
but the driver is the correct place.

Signed-off-by: Thomas Zimmermann <[email protected]>
---
  drivers/gpu/drm/tiny/simpledrm.c | 20 +++++++++++++++-----
  1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/tiny/simpledrm.c b/drivers/gpu/drm/tiny/simpledrm.c
index 04146da2d1d8..f72b71511a65 100644
--- a/drivers/gpu/drm/tiny/simpledrm.c
+++ b/drivers/gpu/drm/tiny/simpledrm.c
@@ -526,21 +526,31 @@ static int simpledrm_device_init_mm(struct 
simpledrm_device *sdev)
  {
        struct drm_device *dev = &sdev->dev;
        struct platform_device *pdev = sdev->pdev;
-       struct resource *mem;
+       struct resource *res, *mem;
        void __iomem *screen_base;
        int ret;
- mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-       if (!mem)
+       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+       if (!res)
                return -EINVAL;
- ret = devm_aperture_acquire_from_firmware(dev, mem->start, resource_size(mem));
+       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",
-                       mem, ret);
+                       res, ret);
                return ret;
        }
+ mem = devm_request_mem_region(&pdev->dev, res->start, resource_size(res),
+                                     sdev->dev.driver->name);
+       if (!mem) {
+               /*
+                * We cannot make this fatal. Sometimes this comes from magic
+                * spaces our resource handlers simply don't know about
+                */
+               drm_warn(dev, "could not acquire memory region %pr\n", res);
+       }
+
        screen_base = devm_ioremap_wc(&pdev->dev, mem->start,
                                      resource_size(mem));

if mem is NULL, accessing mem->start will segfault after the warning.
I think you renamed "mem" to "res" so probably it should be renamed here too ?

        if (!screen_base)

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