linux-kernel - [PATCH] video: hyperv_fb: Allow resolutions with size

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Message-Id: <1651067273-6635-1-git-send-email-ssengar@linux.microsoft.com>
Date:   Wed, 27 Apr 2022 06:47:53 -0700
From:   Saurabh Sengar <ssengar@...ux.microsoft.com>
To:     ssengar@...rosoft.com, kys@...rosoft.com, haiyangz@...rosoft.com,
        sthemmin@...rosoft.com, wei.liu@...nel.org, decui@...rosoft.com,
        deller@....de, linux-hyperv@...r.kernel.org,
        linux-fbdev@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] video: hyperv_fb: Allow resolutions with size > 64 MB for Gen1

This patch fixes a bug where GEN1 VMs doesn't allow resolutions greater
than 64 MB size (eg 7680x4320). Unnecessary PCI check limits Gen1 VRAM
to legacy PCI BAR size only (ie 64MB). Thus any, resolution requesting
greater then 64MB (eg 7680x4320) would fail. MMIO region assigning this
memory shouldn't be limited by PCI bar size.

Signed-off-by: Saurabh Sengar <ssengar@...ux.microsoft.com>
---
 drivers/video/fbdev/hyperv_fb.c | 19 +------------------
 1 file changed, 1 insertion(+), 18 deletions(-)

diff --git a/drivers/video/fbdev/hyperv_fb.c b/drivers/video/fbdev/hyperv_fb.c
index c8e0ea2..58c304a 100644
--- a/drivers/video/fbdev/hyperv_fb.c
+++ b/drivers/video/fbdev/hyperv_fb.c
@@ -1009,7 +1009,6 @@ static int hvfb_getmem(struct hv_device *hdev, struct fb_info *info)
 	struct pci_dev *pdev  = NULL;
 	void __iomem *fb_virt;
 	int gen2vm = efi_enabled(EFI_BOOT);
-	resource_size_t pot_start, pot_end;
 	phys_addr_t paddr;
 	int ret;
 
@@ -1060,23 +1059,7 @@ static int hvfb_getmem(struct hv_device *hdev, struct fb_info *info)
 	dio_fb_size =
 		screen_width * screen_height * screen_depth / 8;
 
-	if (gen2vm) {
-		pot_start = 0;
-		pot_end = -1;
-	} else {
-		if (!(pci_resource_flags(pdev, 0) & IORESOURCE_MEM) ||
-		    pci_resource_len(pdev, 0) < screen_fb_size) {
-			pr_err("Resource not available or (0x%lx < 0x%lx)\n",
-			       (unsigned long) pci_resource_len(pdev, 0),
-			       (unsigned long) screen_fb_size);
-			goto err1;
-		}
-
-		pot_end = pci_resource_end(pdev, 0);
-		pot_start = pot_end - screen_fb_size + 1;
-	}
-
-	ret = vmbus_allocate_mmio(&par->mem, hdev, pot_start, pot_end,
+	ret = vmbus_allocate_mmio(&par->mem, hdev, 0, -1,
 				  screen_fb_size, 0x100000, true);
 	if (ret != 0) {
 		pr_err("Unable to allocate framebuffer memory\n");
-- 
1.8.3.1