diff options
Diffstat (limited to 'pc-bios/openbios-esp.diff')
| -rw-r--r-- | pc-bios/openbios-esp.diff | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/pc-bios/openbios-esp.diff b/pc-bios/openbios-esp.diff new file mode 100644 index 0000000000..5d4f836f12 --- /dev/null +++ b/pc-bios/openbios-esp.diff @@ -0,0 +1,30 @@ +The ESP SCSI driver currently doesn't check whether a DMA requests has +completed before checking its status. On older qemu versions this works ok +because DMA happens instantly. On never qemu DMA can take an indeterminate +amount of time ooto complete, just like on real hardware. + +The patch below waits for the controller to raise the DMA interrupt after +initiating a DMA request. + +Index: drivers/esp.c +=================================================================== +--- drivers/esp.c (revision 61) ++++ drivers/esp.c (working copy) +@@ -113,6 +113,8 @@ do_command(esp_private_t *esp, sd_privat + esp->espdma.regs->cond_reg = 0; + // Set ATN, issue command + esp->ll->regs[ESP_CMD] = ESP_CMD_SELA | ESP_CMD_DMA; ++ // Wait for DMA to complete ++ while ((esp->espdma.regs->cond_reg & DMA_HNDL_INTR) == 0) /* no-op */; + // Check status + status = esp->ll->regs[ESP_STATUS]; + +@@ -129,6 +131,8 @@ do_command(esp_private_t *esp, sd_privat + esp->espdma.regs->cond_reg = DMA_ST_WRITE; + // Transfer + esp->ll->regs[ESP_CMD] = ESP_CMD_TI | ESP_CMD_DMA; ++ // Wait for DMA to complete ++ while ((esp->espdma.regs->cond_reg & DMA_HNDL_INTR) == 0) /* no-op */; + // Check status + status = esp->ll->regs[ESP_STATUS]; + |