On 3/10/2021 4:38 AM, Loic Poulain wrote:
Some buggy hardwares (e.g sdx24) may report the current command
ring wp pointer instead of the command completion pointer. It's
obviously wrong, causing completion timeout. We can however deal
with that situation by completing the cmd n-1 element, which is
what the device actually completes.
Signed-off-by: Loic Poulain <loic.poulain@xxxxxxxxxx>
---
drivers/bus/mhi/core/main.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
index 16b9640..3e3c520 100644
--- a/drivers/bus/mhi/core/main.c
+++ b/drivers/bus/mhi/core/main.c
@@ -707,6 +707,7 @@ static void mhi_process_cmd_completion(struct mhi_controller *mhi_cntrl,
{
dma_addr_t ptr = MHI_TRE_GET_EV_PTR(tre);
struct mhi_cmd *cmd_ring = &mhi_cntrl->mhi_cmd[PRIMARY_CMD_RING];
+ struct device *dev = &mhi_cntrl->mhi_dev->dev;
struct mhi_ring *mhi_ring = &cmd_ring->ring;
struct mhi_tre *cmd_pkt;
struct mhi_chan *mhi_chan;
@@ -714,6 +715,23 @@ static void mhi_process_cmd_completion(struct mhi_controller *mhi_cntrl,
cmd_pkt = mhi_to_virtual(mhi_ring, ptr);
+ if (unlikely(cmd_pkt == mhi_ring->wp)) {
+ /* Some buggy hardwares (e.g sdx24) sometimes report the current
+ * command ring wp pointer instead of the command completion
+ * pointer. It's obviously wrong, causing completion timeout. We
+ * can however deal with that situation by completing the cmd
+ * n-1 element.
+ */
+ void *ring_ptr = (void *)cmd_pkt - mhi_ring->el_size;
+
+ if (ring_ptr < mhi_ring->base)
+ ring_ptr += mhi_ring->len;
+
+ cmd_pkt = ring_ptr;
+
+ dev_warn(dev, "Bad completion pointer (ptr == ring_wp)\n");
Is there value in having this warning every time? I wonder if a _once
version would be better to not flood the kernel log. Although this is
only for commands, which shouldn't be frequent, so maybe that is the
implicit rate limiter.
What do you think?
+ }
+
chan = MHI_TRE_GET_CMD_CHID(cmd_pkt);
mhi_chan = &mhi_cntrl->mhi_chan[chan];
write_lock_bh(&mhi_chan->lock);
--
Jeffrey Hugo
Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.
