i3c: mipi-i3c-hci: Add Intel specific quirk to ring resuming

MIPI I3C HCI on Intel hardware requires a quirk where ring needs to stop
and set to run again after resuming the halted controller. This is not
expected from the MIPI I3C HCI specification and is Intel specific.

Add this quirk to generic aborted transfer handling and execute it only
when ring is not in running state after a transfer error and attempted
controller resume. This is the case on Intel hardware.

It is not fully clear to me what is the ring running state in generic
hardware in such case. I would expect if ring is not running, then stop
request is a no-op and run request is either required or does the same
what controller resume would do.

Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Link: https://lore.kernel.org/r/20241231115904.620052-1-jarkko.nikula@linux.intel.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

diff --git a/drivers/i3c/master/mipi-i3c-hci/dma.c b/drivers/i3c/master/mipi-i3c-hci/dma.c
index e8e56a8d20573f1d1318cf98afb14f8db15cd0f7..491dfe70b660029ca52d25f06512b6a7afa96c82 100644 (file)
--- a/drivers/i3c/master/mipi-i3c-hci/dma.c
+++ b/drivers/i3c/master/mipi-i3c-hci/dma.c
@@ -758,9 +758,26 @@ static bool hci_dma_irq_handler(struct i3c_hci *hci)
                        complete(&rh->op_done);
 
                if (status & INTR_TRANSFER_ABORT) {
+                       u32 ring_status;
+
                        dev_notice_ratelimited(&hci->master.dev,
                                "ring %d: Transfer Aborted\n", i);
                        mipi_i3c_hci_resume(hci);
+                       ring_status = rh_reg_read(RING_STATUS);
+                       if (!(ring_status & RING_STATUS_RUNNING) &&
+                           status & INTR_TRANSFER_COMPLETION &&
+                           status & INTR_TRANSFER_ERR) {
+                               /*
+                                * Ring stop followed by run is an Intel
+                                * specific required quirk after resuming the
+                                * halted controller. Do it only when the ring
+                                * is not in running state after a transfer
+                                * error.
+                                */
+                               rh_reg_write(RING_CONTROL, RING_CTRL_ENABLE);
+                               rh_reg_write(RING_CONTROL, RING_CTRL_ENABLE |
+                                                          RING_CTRL_RUN_STOP);
+                       }
                }
                if (status & INTR_WARN_INS_STOP_MODE)
                        dev_warn_ratelimited(&hci->master.dev,