linux-kernel - [PATCH 1/1] fbdev/hyperv_fb: Fix logic error for Gen2 VMs in hvfb

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Date: Wed, 31 Jan 2024 22:00:22 -0800
From: mhkelley58@...il.com
To: haiyangz@...rosoft.com,
	wei.liu@...nel.org,
	decui@...rosoft.com,
	drawat.floss@...il.com,
	javierm@...hat.com,
	deller@....de,
	daniel@...ll.ch,
	airlied@...il.com,
	tzimmermann@...e.de
Cc: dri-devel@...ts.freedesktop.org,
	linux-fbdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-hyperv@...r.kernel.org
Subject: [PATCH 1/1] fbdev/hyperv_fb: Fix logic error for Gen2 VMs in hvfb_getmem()

From: Michael Kelley <mhklinux@...look.com>

A recent commit removing the use of screen_info introduced a logic
error. The error causes hvfb_getmem() to always return -ENOMEM
for Generation 2 VMs. As a result, the Hyper-V frame buffer
device fails to initialize. The error was introduced by removing
an "else if" clause, leaving Gen2 VMs to always take the -ENOMEM
error path.

Fix the problem by removing the error path "else" clause. Gen 2
VMs now always proceed through the MMIO memory allocation code,
but with "base" and "size" defaulting to 0.

Fixes: 0aa0838c84da ("fbdev/hyperv_fb: Remove firmware framebuffers with aperture helpers")
Signed-off-by: Michael Kelley <mhklinux@...look.com>
---
 drivers/video/fbdev/hyperv_fb.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/video/fbdev/hyperv_fb.c b/drivers/video/fbdev/hyperv_fb.c
index c26ee6fd73c9..8fdccf033b2d 100644
--- a/drivers/video/fbdev/hyperv_fb.c
+++ b/drivers/video/fbdev/hyperv_fb.c
@@ -1010,8 +1010,6 @@ static int hvfb_getmem(struct hv_device *hdev, struct fb_info *info)
 			goto getmem_done;
 		}
 		pr_info("Unable to allocate enough contiguous physical memory on Gen 1 VM. Using MMIO instead.\n");
-	} else {
-		goto err1;
 	}
 
 	/*
-- 
2.25.1