diff options
Diffstat (limited to 'drivers/gpu/drm/udl/udl_transfer.c')
| -rw-r--r-- | drivers/gpu/drm/udl/udl_transfer.c | 216 |
1 files changed, 216 insertions, 0 deletions
diff --git a/drivers/gpu/drm/udl/udl_transfer.c b/drivers/gpu/drm/udl/udl_transfer.c new file mode 100644 index 000000000..b57844632 --- /dev/null +++ b/drivers/gpu/drm/udl/udl_transfer.c @@ -0,0 +1,216 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2012 Red Hat + * based in parts on udlfb.c: + * Copyright (C) 2009 Roberto De Ioris <roberto@unbit.it> + * Copyright (C) 2009 Jaya Kumar <jayakumar.lkml@gmail.com> + * Copyright (C) 2009 Bernie Thompson <bernie@plugable.com> + */ + +#include <asm/unaligned.h> + +#include "udl_drv.h" + +#define MAX_CMD_PIXELS 255 + +#define RLX_HEADER_BYTES 7 +#define MIN_RLX_PIX_BYTES 4 +#define MIN_RLX_CMD_BYTES (RLX_HEADER_BYTES + MIN_RLX_PIX_BYTES) + +#define RLE_HEADER_BYTES 6 +#define MIN_RLE_PIX_BYTES 3 +#define MIN_RLE_CMD_BYTES (RLE_HEADER_BYTES + MIN_RLE_PIX_BYTES) + +#define RAW_HEADER_BYTES 6 +#define MIN_RAW_PIX_BYTES 2 +#define MIN_RAW_CMD_BYTES (RAW_HEADER_BYTES + MIN_RAW_PIX_BYTES) + +static inline u16 pixel32_to_be16(const uint32_t pixel) +{ + return (((pixel >> 3) & 0x001f) | + ((pixel >> 5) & 0x07e0) | + ((pixel >> 8) & 0xf800)); +} + +static inline u16 get_pixel_val16(const uint8_t *pixel, int log_bpp) +{ + u16 pixel_val16; + if (log_bpp == 1) + pixel_val16 = *(const uint16_t *)pixel; + else + pixel_val16 = pixel32_to_be16(*(const uint32_t *)pixel); + return pixel_val16; +} + +/* + * Render a command stream for an encoded horizontal line segment of pixels. + * + * A command buffer holds several commands. + * It always begins with a fresh command header + * (the protocol doesn't require this, but we enforce it to allow + * multiple buffers to be potentially encoded and sent in parallel). + * A single command encodes one contiguous horizontal line of pixels + * + * The function relies on the client to do all allocation, so that + * rendering can be done directly to output buffers (e.g. USB URBs). + * The function fills the supplied command buffer, providing information + * on where it left off, so the client may call in again with additional + * buffers if the line will take several buffers to complete. + * + * A single command can transmit a maximum of 256 pixels, + * regardless of the compression ratio (protocol design limit). + * To the hardware, 0 for a size byte means 256 + * + * Rather than 256 pixel commands which are either rl or raw encoded, + * the rlx command simply assumes alternating raw and rl spans within one cmd. + * This has a slightly larger header overhead, but produces more even results. + * It also processes all data (read and write) in a single pass. + * Performance benchmarks of common cases show it having just slightly better + * compression than 256 pixel raw or rle commands, with similar CPU consumpion. + * But for very rl friendly data, will compress not quite as well. + */ +static void udl_compress_hline16( + const u8 **pixel_start_ptr, + const u8 *const pixel_end, + uint32_t *device_address_ptr, + uint8_t **command_buffer_ptr, + const uint8_t *const cmd_buffer_end, int log_bpp) +{ + const int bpp = 1 << log_bpp; + const u8 *pixel = *pixel_start_ptr; + uint32_t dev_addr = *device_address_ptr; + uint8_t *cmd = *command_buffer_ptr; + + while ((pixel_end > pixel) && + (cmd_buffer_end - MIN_RLX_CMD_BYTES > cmd)) { + uint8_t *raw_pixels_count_byte = NULL; + uint8_t *cmd_pixels_count_byte = NULL; + const u8 *raw_pixel_start = NULL; + const u8 *cmd_pixel_start, *cmd_pixel_end = NULL; + uint16_t pixel_val16; + + *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_pixels_count_byte = cmd++; /* we'll know this later */ + cmd_pixel_start = pixel; + + raw_pixels_count_byte = cmd++; /* we'll know this later */ + raw_pixel_start = pixel; + + cmd_pixel_end = pixel + (min3(MAX_CMD_PIXELS + 1UL, + (unsigned long)(pixel_end - pixel) >> log_bpp, + (unsigned long)(cmd_buffer_end - 1 - cmd) / 2) << log_bpp); + + pixel_val16 = get_pixel_val16(pixel, log_bpp); + + while (pixel < cmd_pixel_end) { + const u8 *const start = pixel; + const uint16_t repeating_pixel_val16 = pixel_val16; + + put_unaligned_be16(pixel_val16, cmd); + + cmd += 2; + pixel += bpp; + + while (pixel < cmd_pixel_end) { + pixel_val16 = get_pixel_val16(pixel, log_bpp); + if (pixel_val16 != repeating_pixel_val16) + break; + pixel += bpp; + } + + if (unlikely(pixel > start + bpp)) { + /* go back and fill in raw pixel count */ + *raw_pixels_count_byte = (((start - + raw_pixel_start) >> log_bpp) + 1) & 0xFF; + + /* immediately after raw data is repeat byte */ + *cmd++ = (((pixel - start) >> log_bpp) - 1) & 0xFF; + + /* Then start another raw pixel span */ + raw_pixel_start = pixel; + raw_pixels_count_byte = cmd++; + } + } + + if (pixel > raw_pixel_start) { + /* finalize last RAW span */ + *raw_pixels_count_byte = ((pixel - raw_pixel_start) >> log_bpp) & 0xFF; + } else { + /* undo unused byte */ + cmd--; + } + + *cmd_pixels_count_byte = ((pixel - cmd_pixel_start) >> log_bpp) & 0xFF; + dev_addr += ((pixel - cmd_pixel_start) >> log_bpp) * 2; + } + + if (cmd_buffer_end <= MIN_RLX_CMD_BYTES + cmd) { + /* Fill leftover bytes with no-ops */ + if (cmd_buffer_end > cmd) + memset(cmd, 0xAF, cmd_buffer_end - cmd); + cmd = (uint8_t *) cmd_buffer_end; + } + + *command_buffer_ptr = cmd; + *pixel_start_ptr = pixel; + *device_address_ptr = dev_addr; + + return; +} + +/* + * There are 3 copies of every pixel: The front buffer that the fbdev + * client renders to, the actual framebuffer across the USB bus in hardware + * (that we can only write to, slowly, and can never read), and (optionally) + * our shadow copy that tracks what's been sent to that hardware buffer. + */ +int udl_render_hline(struct drm_device *dev, int log_bpp, struct urb **urb_ptr, + const char *front, char **urb_buf_ptr, + u32 byte_offset, u32 device_byte_offset, + u32 byte_width) +{ + const u8 *line_start, *line_end, *next_pixel; + u32 base16 = 0 + (device_byte_offset >> log_bpp) * 2; + struct urb *urb = *urb_ptr; + u8 *cmd = *urb_buf_ptr; + u8 *cmd_end = (u8 *) urb->transfer_buffer + urb->transfer_buffer_length; + + if (WARN_ON(!(log_bpp == 1 || log_bpp == 2))) { + /* need to finish URB at error from this function */ + udl_urb_completion(urb); + return -EINVAL; + } + + line_start = (u8 *) (front + byte_offset); + next_pixel = line_start; + line_end = next_pixel + byte_width; + + while (next_pixel < line_end) { + + udl_compress_hline16(&next_pixel, + line_end, &base16, + (u8 **) &cmd, (u8 *) cmd_end, log_bpp); + + if (cmd >= cmd_end) { + int len = cmd - (u8 *) urb->transfer_buffer; + int ret = udl_submit_urb(dev, urb, len); + if (ret) + return ret; + urb = udl_get_urb(dev); + if (!urb) + return -EAGAIN; + *urb_ptr = urb; + cmd = urb->transfer_buffer; + cmd_end = &cmd[urb->transfer_buffer_length]; + } + } + + *urb_buf_ptr = cmd; + + return 0; +} |