Driver generates lots of alignment trap exceptions on ARM.
Fix that by replacing typecasting of odd addresses with
byte shifting and remove uneccessary typecasting.
Signed-off-by: Ladislav Michl <ladis@xxxxxxxxxxxxxx>
---
Here's what happens on at91sam9g20 few minutes after boot:
$ cat /proc/cpu/alignment
User: 0
System: 10747836 (dlfb_render_hline+0x22c/0x2f0 [udlfb])
Skipped: 0
Half: 10747971
Word: 159
DWord: 0
Multi: 0
Each hline transfer causes dozens alignment exceptions and
few are in dlfb_parse_vendor_descriptor function.
drivers/video/fbdev/udlfb.c | 23 ++++++++++++-----------
1 file changed, 12 insertions(+), 11 deletions(-)
diff --git a/drivers/video/fbdev/udlfb.c b/drivers/video/fbdev/udlfb.c
index 452a4207ac1b..45081297efa5 100644
--- a/drivers/video/fbdev/udlfb.c
+++ b/drivers/video/fbdev/udlfb.c
@@ -441,9 +441,9 @@ static void dlfb_compress_hline(
*cmd++ = 0xAF;
*cmd++ = 0x6B;
- *cmd++ = (uint8_t) ((dev_addr >> 16) & 0xFF);
- *cmd++ = (uint8_t) ((dev_addr >> 8) & 0xFF);
- *cmd++ = (uint8_t) ((dev_addr) & 0xFF);
+ *cmd++ = dev_addr >> 16;
+ *cmd++ = dev_addr >> 8;
+ *cmd++ = dev_addr;
cmd_pixels_count_byte = cmd++; /* we'll know this later */
cmd_pixel_start = pixel;
@@ -460,8 +460,8 @@ static void dlfb_compress_hline(
while (pixel < cmd_pixel_end) {
const uint16_t * const repeating_pixel = pixel;
- *(uint16_t *)cmd = cpu_to_be16p(pixel);
- cmd += 2;
+ *cmd++ = *pixel >> 8;
+ *cmd++ = *pixel;
pixel++;
if (unlikely((pixel < cmd_pixel_end) &&
@@ -1531,15 +1531,16 @@ static int dlfb_parse_vendor_descriptor(struct dlfb_data *dlfb,
u8 length;
u16 key;
- key = le16_to_cpu(*((u16 *) desc));
- desc += sizeof(u16);
- length = *desc;
- desc++;
+ key = *desc++;
+ key |= (u16)*desc++ << 8;
+ length = *desc++;
switch (key) {
case 0x0200: { /* max_area */
- u32 max_area;
- max_area = le32_to_cpu(*((u32 *)desc));
+ u32 max_area = *desc++;
+ max_area |= (u32)*desc++ << 8;
+ max_area |= (u32)*desc++ << 16;
+ max_area |= (u32)*desc++ << 24;
dev_warn(&intf->dev,
"DL chip limited to %d pixel modes\n",
max_area);
--
2.16.1
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