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 f4cae5357e400cd0a8b1338e955a6c3b9cf20eef..3e90ddcbb24a74732e2dc184a3272e95348681dc 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c
@@ -1575,34 +1575,32 @@ void amdgpu_atombios_scratch_regs_restore(struct amdgpu_device *adev)
                WREG32(mmBIOS_SCRATCH_0 + i, adev->bios_scratch[i]);
 }
 
-/* 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 b5760851195cfbcb0cfca10a88a154b38436c0b6..0c6216a6ee9e0a4da0691d619c2e28728a295cde 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);