Re: [PATCH 5/5] hw/display/artist: Fix framebuffer access for Linux

[Philippe Mathieu-Daudé]

+Sven

On 12/1/22 22:07, Helge Deller wrote:
This patch fixes two problems which prevented Linux to access the
artist graphics framebuffer:
The check if the framebuffer or the color map should be accessed was
incomplete. By using the vram_read/write_bufidx() functions we now check
correctly if ARTIST_BUFFER_CMAP should be accessed.

The second fix is to correctly calculate the X- and Y-coordinates and
check against the graphics resolution.

With this fix in place, the Linux stifb driver now works correctly,
shows the penguins at bootup and uses the stifb as graphics console.

Cool, could you add a test similar to these?

$ git grep Tux tests/avocado/
tests/avocado/machine_arm_integratorcp.py:69:        Boot Linux and 
verify the Tux logo is displayed on the framebuffer.
tests/avocado/machine_mips_malta.py:44:        Boot Linux kernel and 
check Tux logo is displayed on the framebuffer.

I haven't seen any negative side effects when running HP-UX.

Signed-off-by: Helge Deller <del...@gmx.de>
Cc: qemu-sta...@nongnu.org
---
  hw/display/artist.c | 16 ++++++++--------
  1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/hw/display/artist.c b/hw/display/artist.c
index 6384076c60..fbf5525334 100644
--- a/hw/display/artist.c
+++ b/hw/display/artist.c
@@ -1186,7 +1186,7 @@ static void artist_vram_write(void *opaque, hwaddr addr, 
uint64_t val,
      unsigned int offset;
      trace_artist_vram_write(size, addr, val);

-    if (s->cmap_bm_access) {
+    if (vram_write_bufidx(s) == ARTIST_BUFFER_CMAP) {
          buf = &s->vram_buffer[ARTIST_BUFFER_CMAP];
          if (addr + 3 < buf->size) {
              *(uint32_t *)(buf->data + addr) = val;
@@ -1195,14 +1195,14 @@ static void artist_vram_write(void *opaque, hwaddr 
addr, uint64_t val,
      }

      buf = vram_write_buffer(s);
-    posy = ADDR_TO_Y(addr >> 2);
-    posx = ADDR_TO_X(addr >> 2);
+    posy = ADDR_TO_Y(addr);
+    posx = ADDR_TO_X(addr);

      if (!buf->size) {
          return;
      }

-    if (posy > buf->height || posx > buf->width) {
+    if (posy >= buf->height || posx >= buf->width) {
          return;
      }

@@ -1242,7 +1242,7 @@ static uint64_t artist_vram_read(void *opaque, hwaddr 
addr, unsigned size)
      uint64_t val;
      unsigned int posy, posx;

-    if (s->cmap_bm_access) {
+    if (vram_read_bufidx(s) == ARTIST_BUFFER_CMAP) {
          buf = &s->vram_buffer[ARTIST_BUFFER_CMAP];
          val = 0;
          if (addr < buf->size && addr + 3 < buf->size) {
@@ -1257,10 +1257,10 @@ static uint64_t artist_vram_read(void *opaque, hwaddr 
addr, unsigned size)
          return 0;
      }

-    posy = ADDR_TO_Y(addr >> 2);
-    posx = ADDR_TO_X(addr >> 2);
+    posy = ADDR_TO_Y(addr);
+    posx = ADDR_TO_X(addr);

-    if (posy > buf->height || posx > buf->width) {
+    if (posy >= buf->height || posx >= buf->width) {
          return 0;
      }

--
2.31.1