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Commit e90a4ea5 authored by Chris Wilson's avatar Chris Wilson Committed by Dave Airlie
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drm/udl: Inline memcmp() for RLE compression of xfer 



As we use a variable length the compiler does not realise that it is a
fixed value of either 2 or 4 bytes. Instead of performing the inline
comparison itself, the compiler inserts a function call to the generic
memcmp routine which is optimised for long comparisons of variable
length. That turns out to be quite expensive...

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: default avatarDave Airlie <airlied@redhat.com>
parent bcb39af4

drivers/gpu/drm/udl/udl_transfer.c

+28 −18
Original line number Diff line number Diff line
@@ -75,15 +75,19 @@ static int udl_trim_hline(const u8 *bback, const u8 **bfront, int *width_bytes) 
}

#endif



static inline u16 pixel32_to_be16p(const uint8_t *pixel)

static inline u16 pixel32_to_be16(const uint32_t pixel)

{

	uint32_t pix = *(uint32_t *)pixel;

	u16 retval;

	return (((pixel >> 3) & 0x001f) |

		((pixel >> 5) & 0x07e0) |

		((pixel >> 8) & 0xf800));

}



	retval =  (((pix >> 3) & 0x001f) |

		   ((pix >> 5) & 0x07e0) |

		   ((pix >> 8) & 0xf800));

	return retval;

static bool pixel_repeats(const void *pixel, const uint32_t repeat, int bpp)

{

	if (bpp == 2)

		return *(const uint16_t *)pixel == repeat;

	else

		return *(const uint32_t *)pixel == repeat;

}



/*
@@ -152,29 +156,33 @@ static void udl_compress_hline16( 
		prefetch_range((void *) pixel, (cmd_pixel_end - pixel) * bpp);



		while (pixel < cmd_pixel_end) {

			const u8 * const repeating_pixel = pixel;



			if (bpp == 2)

				*(uint16_t *)cmd = cpu_to_be16p((uint16_t *)pixel);

			else if (bpp == 4)

				*(uint16_t *)cmd = cpu_to_be16(pixel32_to_be16p(pixel));

			const u8 *const start = pixel;

			u32 repeating_pixel;



			if (bpp == 2) {

				repeating_pixel = *(uint16_t *)pixel;

				*(uint16_t *)cmd = cpu_to_be16(repeating_pixel);

			} else {

				repeating_pixel = *(uint32_t *)pixel;

				*(uint16_t *)cmd = cpu_to_be16(pixel32_to_be16(repeating_pixel));

			}



			cmd += 2;

			pixel += bpp;



			if (unlikely((pixel < cmd_pixel_end) &&

				     (!memcmp(pixel, repeating_pixel, bpp)))) {

				     (pixel_repeats(pixel, repeating_pixel, bpp)))) {

				/* go back and fill in raw pixel count */

				*raw_pixels_count_byte = (((repeating_pixel -

				*raw_pixels_count_byte = (((start -

						raw_pixel_start) / bpp) + 1) & 0xFF;



				while ((pixel < cmd_pixel_end)

				       && (!memcmp(pixel, repeating_pixel, bpp))) {

				while ((pixel < cmd_pixel_end) &&

				       (pixel_repeats(pixel, repeating_pixel, bpp))) {

					pixel += bpp;

				}



				/* immediately after raw data is repeat byte */

				*cmd++ = (((pixel - repeating_pixel) / bpp) - 1) & 0xFF;

				*cmd++ = (((pixel - start) / bpp) - 1) & 0xFF;



				/* Then start another raw pixel span */

				raw_pixel_start = pixel;
@@ -223,6 +231,8 @@ int udl_render_hline(struct drm_device *dev, int bpp, struct urb **urb_ptr, 
	u8 *cmd = *urb_buf_ptr;

	u8 *cmd_end = (u8 *) urb->transfer_buffer + urb->transfer_buffer_length;



	BUG_ON(!(bpp == 2 || bpp == 4));



	line_start = (u8 *) (front + byte_offset);

	next_pixel = line_start;

	line_end = next_pixel + byte_width;