Re: [PATCH] fbdev: xilinxfb: request memory region before mapping framebuffer

Hi
No, this wasn't tested on actual hardware. I don't have access to it.
If someone is able to do it, that would be great.

Thanks
Diviyam


On Tue, 30 Dec 2025 at 23:21, Diviyam Pat [off-list ref] wrote:

Hi
No, this wasn't tested on actual hardware. I don't have access to it. If someone is able to it that would be great.

Thanks
Diviyam

On Tue, 30 Dec, 2025, 3:27 pm Helge Deller, [off-list ref] wrote:

quoted

On 12/15/25 23:53, patdiviyam@gmail.com wrote:

quoted

From: DiviyamPathak <redacted>

The xilinxfb driver maps a physical framebuffer address with ioremap()
without first reserving the memory region. This can conflict with other
drivers accessing the same resource.

Request the memory region with devm_request_mem_region() before mapping
the framebuffer and use managed mappings for proper lifetime handling.

This addresses the fbdev TODO about requesting memory regions and avoids
potential resource conflicts.

Signed-off-by: DiviyamPathak <redacted>

Was it tested it on physical hardware?
If not, could someone test?

Helge

quoted

---
  drivers/video/fbdev/xilinxfb.c | 30 +++++++++++++++++-------------
  1 file changed, 17 insertions(+), 13 deletions(-)

diff --git a/drivers/video/fbdev/xilinxfb.c b/drivers/video/fbdev/xilinxfb.c
index 0a6e05cd155a..f18437490de8 100644
--- a/drivers/video/fbdev/xilinxfb.c
+++ b/drivers/video/fbdev/xilinxfb.c

@@ -280,19 +280,27 @@ static int xilinxfb_assign(struct platform_device *pdev,
      /* Allocate the framebuffer memory */
      if (pdata->fb_phys) {
              drvdata->fb_phys = pdata->fb_phys;
-             drvdata->fb_virt = ioremap(pdata->fb_phys, fbsize);
+             /* Request the memory region before mapping */
+             if (!devm_request_mem_region(dev, pdata->fb_phys, fbsize,
+                                     DRIVER_NAME)) {
+                     dev_err(dev, "Cannot request framebuffer memory region\n");
+                     return -EBUSY;
+             }
+             drvdata->fb_virt = devm_ioremap(dev, pdata->fb_phys, fbsize);
+             if (!drvdata->fb_virt) {
+                     dev_err(dev, "Could not map framebuffer memory\n");
+                     return -ENOMEM;
+             }
      } else {
              drvdata->fb_alloced = 1;
              drvdata->fb_virt = dma_alloc_coherent(dev, PAGE_ALIGN(fbsize),
-                                                   &drvdata->fb_phys,
-                                                   GFP_KERNEL);
-     }
-
-     if (!drvdata->fb_virt) {
-             dev_err(dev, "Could not allocate frame buffer memory\n");
-             return -ENOMEM;
+                                     &drvdata->fb_phys,
+                                     GFP_KERNEL);
+             if (!drvdata->fb_virt) {
+                     dev_err(dev, "Could not allocate frame buffer memory\n");
+                     return -ENOMEM;
+             }
      }
-
      /* Clear (turn to black) the framebuffer */
      memset_io((void __iomem *)drvdata->fb_virt, 0, fbsize);

@@ -362,8 +370,6 @@ static int xilinxfb_assign(struct platform_device *pdev,
      if (drvdata->fb_alloced)
              dma_free_coherent(dev, PAGE_ALIGN(fbsize), drvdata->fb_virt,
                                drvdata->fb_phys);
-     else
-             iounmap(drvdata->fb_virt);

      /* Turn off the display */
      xilinx_fb_out32(drvdata, REG_CTRL, 0);

@@ -386,8 +392,6 @@ static void xilinxfb_release(struct device *dev)
      if (drvdata->fb_alloced)
              dma_free_coherent(dev, PAGE_ALIGN(drvdata->info.fix.smem_len),
                                drvdata->fb_virt, drvdata->fb_phys);
-     else
-             iounmap(drvdata->fb_virt);

      /* Turn off the display */
      xilinx_fb_out32(drvdata, REG_CTRL, 0);