[PATCH v3 1/2] drm/ofdrm: Convert PCI IDs to CPU endianness for comparing

[Thomas Zimmermann]

Properties of 32-bit integers are returned from the OF device tree
as type __be32. Convert PCI vendor and device IDs from __be32 to host
endianness before comparing them to constants. All relevant machines
are old, big-endian Macintosh systems; hence the bug never happened
in practice.

Fixes sparse warnings shown below.

  drivers/gpu/drm/tiny/ofdrm.c:237:17: warning: restricted __be32 degrades to integer
  drivers/gpu/drm/tiny/ofdrm.c:238:18: warning: restricted __be32 degrades to integer
  drivers/gpu/drm/tiny/ofdrm.c:238:54: warning: restricted __be32 degrades to integer

See [1] for the bug report.

v2:
	* convert endianness (Alex)

Reported-by: kernel test robot <lkp at intel.com>
Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
Reviewed-by: Javier Martinez Canillas <javierm at redhat.com>
Link: https://lore.kernel.org/dri-devel/202210192208.D888I6X7-lkp@intel.com/ # [1]
---
 drivers/gpu/drm/tiny/ofdrm.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/tiny/ofdrm.c b/drivers/gpu/drm/tiny/ofdrm.c
index 0e1cc2369afcc..44f13a2b372be 100644
--- a/drivers/gpu/drm/tiny/ofdrm.c
+++ b/drivers/gpu/drm/tiny/ofdrm.c
@@ -231,7 +231,7 @@ static u64 display_get_address_of(struct drm_device *dev, struct device_node *of
 	return address;
 }
 
-static bool is_avivo(__be32 vendor, __be32 device)
+static bool is_avivo(u32 vendor, u32 device)
 {
 	/* This will match most R5xx */
 	return (vendor == PCI_VENDOR_ID_ATI) &&
@@ -265,8 +265,13 @@ static enum ofdrm_model display_get_model_of(struct drm_device *dev, struct devi
 		of_parent = of_get_parent(of_node);
 		vendor_p = of_get_property(of_parent, "vendor-id", NULL);
 		device_p = of_get_property(of_parent, "device-id", NULL);
-		if (vendor_p && device_p && is_avivo(*vendor_p, *device_p))
-			model = OFDRM_MODEL_AVIVO;
+		if (vendor_p && device_p) {
+			u32 vendor = be32_to_cpup(vendor_p);
+			u32 device = be32_to_cpup(device_p);
+
+			if (is_avivo(vendor, device))
+				model = OFDRM_MODEL_AVIVO;
+		}
 		of_node_put(of_parent);
 	} else if (of_device_is_compatible(of_node, "qemu,std-vga")) {
 		model = OFDRM_MODEL_QEMU;
-- 
2.38.0