From 66469319c01a1a36c78d0a8535e3dcbc1349bb19 Mon Sep 17 00:00:00 2001 From: Russell Currey Date: Thu, 15 Dec 2016 16:12:41 +1100 Subject: drivers/gpu/drm/ast: Fix infinite loop if read fails commit 298360af3dab45659810fdc51aba0c9f4097e4f6 upstream. ast_get_dram_info() configures a window in order to access BMC memory. A BMC register can be configured to disallow this, and if so, causes an infinite loop in the ast driver which renders the system unusable. Fix this by erroring out if an error is detected. On powerpc systems with EEH, this leads to the device being fenced and the system continuing to operate. Signed-off-by: Russell Currey Reviewed-by: Joel Stanley Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/20161215051241.20815-1-ruscur@russell.cc Signed-off-by: Greg Kroah-Hartman diff --git a/drivers/gpu/drm/ast/ast_main.c b/drivers/gpu/drm/ast/ast_main.c index 904beaa..f75c642 100644 --- a/drivers/gpu/drm/ast/ast_main.c +++ b/drivers/gpu/drm/ast/ast_main.c @@ -223,7 +223,8 @@ static int ast_get_dram_info(struct drm_device *dev) ast_write32(ast, 0x10000, 0xfc600309); do { - ; + if (pci_channel_offline(dev->pdev)) + return -EIO; } while (ast_read32(ast, 0x10000) != 0x01); data = ast_read32(ast, 0x10004); @@ -428,7 +429,9 @@ int ast_driver_load(struct drm_device *dev, unsigned long flags) ast_detect_chip(dev, &need_post); if (ast->chip != AST1180) { - ast_get_dram_info(dev); + ret = ast_get_dram_info(dev); + if (ret) + goto out_free; ast->vram_size = ast_get_vram_info(dev); DRM_INFO("dram %d %d %d %08x\n", ast->mclk, ast->dram_type, ast->dram_bus_width, ast->vram_size); } -- cgit v0.10.2