[Why] Similar to commit <298360af3> ast_init_dram_reg() 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.

[How] Fix this by erroring out if an error is detected.

Signed-off-by: Defang Bo bodefang@126.com --- drivers/gpu/drm/ast/ast_post.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/ast/ast_post.c b/drivers/gpu/drm/ast/ast_post.c index 8902c2f..ef19c70 100644 --- a/drivers/gpu/drm/ast/ast_post.c +++ b/drivers/gpu/drm/ast/ast_post.c @@ -287,7 +287,9 @@ static void ast_init_dram_reg(struct drm_device *dev) ast_write32(ast, 0x10100, 0xa8);

do { - ; + if (pci_channel_offline(dev->pdev)) + return -EIO; + } while (ast_read32(ast, 0x10100) != 0xa8); } else {/* AST2100/1100 */ if (ast->chip == AST2100 || ast->chip == 2200) @@ -299,12 +301,14 @@ static void ast_init_dram_reg(struct drm_device *dev) ast_write32(ast, 0xf000, 0x1); ast_write32(ast, 0x12000, 0x1688A8A8); do { - ; + if (pci_channel_offline(dev->pdev)) + return -EIO; } while (ast_read32(ast, 0x12000) != 0x01);

ast_write32(ast, 0x10000, 0xfc600309); do { - ; + if (pci_channel_offline(dev->pdev)) + return -EIO; } while (ast_read32(ast, 0x10000) != 0x01); }