[OpenBIOS] [PATCH v3 1/3] esp: clear FIFO before issuing ESP command

[Mark Cave-Ayland]

This ensures that any partially transferred data is removed from the FIFO
before issuing the next ESP command.

Signed-off-by: Mark Cave-Ayland 
---
 drivers/esp.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/esp.c b/drivers/esp.c
index 0880ab2..95e969f 100644
--- a/drivers/esp.c
+++ b/drivers/esp.c
@@ -97,6 +97,8 @@ do_command(esp_private_t *esp, sd_private_t *sd, int cmdlen, int replylen)
     esp->ll->regs[ESP_TCMED] = (cmdlen >> 8) & 0xff;
     // Set DMA direction and enable DMA
     esp->espdma.regs->cond_reg = DMA_ENABLE;
+    // Clear FIFO
+    esp->ll->regs[ESP_CMD] = ESP_CMD_FLUSH;
     // Set ATN, issue command
     esp->ll->regs[ESP_CMD] = ESP_CMD_SELA | ESP_CMD_DMA;
     // Wait for DMA to complete. Can this fail?