[PATCH AUTOSEL 6.12 6/7] i3c: mipi-i3c-hci: Add Intel specific quirk to ring resuming

[Sasha Levin <sashal@kernel.org>]

From: Jarkko Nikula <jarkko.nikula@linux.intel.com>

[ Upstream commit ccdb2e0e3b00d13df90ac7a0524dd855173f1171 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/i3c/master/mipi-i3c-hci/dma.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/i3c/master/mipi-i3c-hci/dma.c b/drivers/i3c/master/mipi-i3c-hci/dma.c
index 13adc58400942..fe955703e59b5 100644
--- a/drivers/i3c/master/mipi-i3c-hci/dma.c
+++ b/drivers/i3c/master/mipi-i3c-hci/dma.c
@@ -762,9 +762,26 @@ static bool hci_dma_irq_handler(struct i3c_hci *hci, unsigned int mask)
 			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,
-- 
2.39.5