drm/radeon: fix atombios on big endian

commit 4f626a4ac8f57ddabf06d03870adab91e463217f upstream.

The function for byteswapping the data send to/from atombios was buggy for
num_bytes not divisible by four. The function must be aware of the fact
that after byte-swapping the u32 units, valid bytes might end up after the
num_bytes boundary.

This patch was tested on kernel 3.12 and allowed us to sucesfully use
DisplayPort on and Radeon SI card. Namely it fixed the link training and
EDID readout.

The function is patched both in radeon and amd drivers, since the functions
and the fixes are identical.

Signed-off-by: Roman Kapl <rka@sysgo.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c
index ce443586a0c71c13bd36472558473c0beae9b081..cc4e18dcd8b6f96abf3eade8a91cbe43ae4660c4 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c
@@ -1766,34 +1766,32 @@ bool amdgpu_atombios_scratch_need_asic_init(struct amdgpu_device *adev)
                return true;
 }
 
-/* Atom needs data in little endian format
- * so swap as appropriate when copying data to
- * or from atom. Note that atom operates on
- * dw units.
+/* Atom needs data in little endian format so swap as appropriate when copying
+ * data to or from atom. Note that atom operates on dw units.
+ *
+ * Use to_le=true when sending data to atom and provide at least
+ * ALIGN(num_bytes,4) bytes in the dst buffer.
+ *
+ * Use to_le=false when receiving data from atom and provide ALIGN(num_bytes,4)
+ * byes in the src buffer.
  */
 void amdgpu_atombios_copy_swap(u8 *dst, u8 *src, u8 num_bytes, bool to_le)
 {
 #ifdef __BIG_ENDIAN
-       u8 src_tmp[20], dst_tmp[20]; /* used for byteswapping */
-       u32 *dst32, *src32;
+       u32 src_tmp[5], dst_tmp[5];
        int i;
+       u8 align_num_bytes = ALIGN(num_bytes, 4);
 
-       memcpy(src_tmp, src, num_bytes);
-       src32 = (u32 *)src_tmp;
-       dst32 = (u32 *)dst_tmp;
        if (to_le) {
-               for (i = 0; i < ((num_bytes + 3) / 4); i++)
-                       dst32[i] = cpu_to_le32(src32[i]);
-               memcpy(dst, dst_tmp, num_bytes);
+               memcpy(src_tmp, src, num_bytes);
+               for (i = 0; i < align_num_bytes / 4; i++)
+                       dst_tmp[i] = cpu_to_le32(src_tmp[i]);
+               memcpy(dst, dst_tmp, align_num_bytes);
        } else {
-               u8 dws = num_bytes & ~3;
-               for (i = 0; i < ((num_bytes + 3) / 4); i++)
-                       dst32[i] = le32_to_cpu(src32[i]);
-               memcpy(dst, dst_tmp, dws);
-               if (num_bytes % 4) {
-                       for (i = 0; i < (num_bytes % 4); i++)
-                               dst[dws+i] = dst_tmp[dws+i];
-               }
+               memcpy(src_tmp, src, align_num_bytes);
+               for (i = 0; i < align_num_bytes / 4; i++)
+                       dst_tmp[i] = le32_to_cpu(src_tmp[i]);
+               memcpy(dst, dst_tmp, num_bytes);
        }
 #else
        memcpy(dst, src, num_bytes);

diff --git a/drivers/gpu/drm/radeon/atombios_dp.c b/drivers/gpu/drm/radeon/atombios_dp.c
index 432cb46f6a34a10753e30317562ce2df5315a890..fd7682bf335dcc2b9760c980827233325797cb82 100644 (file)
--- a/drivers/gpu/drm/radeon/atombios_dp.c
+++ b/drivers/gpu/drm/radeon/atombios_dp.c
@@ -45,34 +45,32 @@ static char *pre_emph_names[] = {
 
 /***** radeon AUX functions *****/
 
-/* Atom needs data in little endian format
- * so swap as appropriate when copying data to
- * or from atom. Note that atom operates on
- * dw units.
+/* Atom needs data in little endian format so swap as appropriate when copying
+ * data to or from atom. Note that atom operates on dw units.
+ *
+ * Use to_le=true when sending data to atom and provide at least
+ * ALIGN(num_bytes,4) bytes in the dst buffer.
+ *
+ * Use to_le=false when receiving data from atom and provide ALIGN(num_bytes,4)
+ * byes in the src buffer.
  */
 void radeon_atom_copy_swap(u8 *dst, u8 *src, u8 num_bytes, bool to_le)
 {
 #ifdef __BIG_ENDIAN
-       u8 src_tmp[20], dst_tmp[20]; /* used for byteswapping */
-       u32 *dst32, *src32;
+       u32 src_tmp[5], dst_tmp[5];
        int i;
+       u8 align_num_bytes = ALIGN(num_bytes, 4);
 
-       memcpy(src_tmp, src, num_bytes);
-       src32 = (u32 *)src_tmp;
-       dst32 = (u32 *)dst_tmp;
        if (to_le) {
-               for (i = 0; i < ((num_bytes + 3) / 4); i++)
-                       dst32[i] = cpu_to_le32(src32[i]);
-               memcpy(dst, dst_tmp, num_bytes);
+               memcpy(src_tmp, src, num_bytes);
+               for (i = 0; i < align_num_bytes / 4; i++)
+                       dst_tmp[i] = cpu_to_le32(src_tmp[i]);
+               memcpy(dst, dst_tmp, align_num_bytes);
        } else {
-               u8 dws = num_bytes & ~3;
-               for (i = 0; i < ((num_bytes + 3) / 4); i++)
-                       dst32[i] = le32_to_cpu(src32[i]);
-               memcpy(dst, dst_tmp, dws);
-               if (num_bytes % 4) {
-                       for (i = 0; i < (num_bytes % 4); i++)
-                               dst[dws+i] = dst_tmp[dws+i];
-               }
+               memcpy(src_tmp, src, align_num_bytes);
+               for (i = 0; i < align_num_bytes / 4; i++)
+                       dst_tmp[i] = le32_to_cpu(src_tmp[i]);
+               memcpy(dst, dst_tmp, num_bytes);
        }
 #else
        memcpy(dst, src, num_bytes);