-----Original Message----- From: Wei Liu wei.liu@kernel.org Sent: Thursday, April 28, 2022 10:38 AM To: Saurabh Sengar ssengar@linux.microsoft.com Cc: Saurabh Singh Sengar ssengar@microsoft.com; KY Srinivasan kys@microsoft.com; Haiyang Zhang haiyangz@microsoft.com; Stephen Hemminger sthemmin@microsoft.com; wei.liu@kernel.org; Dexuan Cui decui@microsoft.com; deller@gmx.de; linux-hyperv@vger.kernel.org; linux- fbdev@vger.kernel.org; dri-devel@lists.freedesktop.org; linux- kernel@vger.kernel.org Subject: Re: [PATCH] video: hyperv_fb: Allow resolutions with size > 64 MB for Gen1
On Wed, Apr 27, 2022 at 06:47:53AM -0700, Saurabh Sengar wrote:
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@linux.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;This restriction has been in place since day 1. Haiyang, you wrote this driver. Can you comment on whether this change here is sensible?
When I initially implemented this driver 10 years ago, I believe there was smaller limit for the fb... But I think this patch is good for the newer MMIO alloc scheme. I hope to see reviews also from @Dexuan Cui @Michael Kelley (LINUX) who are more familiar with the PCI/BAR/MMIO area.
Thanks, - Haiyang