arch: arm: mach-socfpga: Mailbox buffer and SDM doorbell improvement
The current write and notify SDM to read mechanism has a flaw where
SDM is not notified enough to be able to read all the data in the buffer.
This is caused by SDM doorbell will only be sent out once the command
buffer overflow check is satisfied. If the command buffer does not reach
overflow status, no SDM doorbell will be sent out, which may cause a
timeout as the mailbox driver will be waiting for the SDM to read the
buffer to empty even though SDM is not notified to do so.
The solution is to remove the command buffer overflow check
and set the SDM doorbell to always trigger at the end of the command
buffer.
This will ensure that the SDM is able to read all of the data.
Signed-off-by: Alif Zakuan Yuslaimi <alif.zakuan.yuslaimi@altera.com>
diff --git a/arch/arm/mach-socfpga/mailbox_s10.c b/arch/arm/mach-socfpga/mailbox_s10.c
index 2b4f260..b69bd3e 100644
--- a/arch/arm/mach-socfpga/mailbox_s10.c
+++ b/arch/arm/mach-socfpga/mailbox_s10.c
@@ -88,6 +88,8 @@
MBOX_WRITE_CMD_BUF(data, (*cin)++);
*cin %= MBOX_CMD_BUFFER_SIZE;
MBOX_WRITEL(*cin, MBOX_CIN);
+ if (is_cmdbuf_overflow)
+ *is_cmdbuf_overflow = 0;
break;
}
timeout--;
@@ -96,10 +98,6 @@
if (!timeout)
return -ETIMEDOUT;
- /* Wait for the SDM to drain the FIFO command buffer */
- if (is_cmdbuf_overflow && *is_cmdbuf_overflow)
- return mbox_wait_for_cmdbuf_empty(*cin);
-
return 0;
}
@@ -125,13 +123,11 @@
return ret;
}
- /* If SDM doorbell is not triggered after the last data is
- * written into mailbox FIFO command buffer, trigger the
- * SDM doorbell again to ensure SDM able to read the remaining
- * data.
+ /*
+ * Always trigger the SDM doorbell at the end to ensure SDM able to read
+ * the remaining data.
*/
- if (!is_cmdbuf_overflow)
- MBOX_WRITEL(1, MBOX_DOORBELL_TO_SDM);
+ MBOX_WRITEL(1, MBOX_DOORBELL_TO_SDM);
return 0;
}