[V11,1/2] i2c: i2c-qcom-geni: Add shutdown callback for i2c

Message ID 20210525131051.31250-2-rojay@codeaurora.org
State Accepted
Commit 9f78c607600ce4f2a952560de26534715236f612
Headers show
Series
  • Implement Shutdown callback for geni_i2c
Related show

Commit Message

Roja Rani Yarubandi May 25, 2021, 1:10 p.m.
If the hardware is still accessing memory after SMMU translation
is disabled (as part of smmu shutdown callback), then the
IOVAs (I/O virtual address) which it was using will go on the bus
as the physical addresses which will result in unknown crashes
like NoC/interconnect errors.

So, implement shutdown callback for i2c driver to suspend the bus
during system "reboot" or "shutdown".

Fixes: 37692de5d523 ("i2c: i2c-qcom-geni: Add bus driver for the Qualcomm GENI I2C controller")
Signed-off-by: Roja Rani Yarubandi <rojay@codeaurora.org>
---
Changes in V2:
 - As per Stephen's comments added seperate function for stop transfer,
   fixed minor nitpicks.
 - As per Stephen's comments, changed commit text.

Changes in V3:
 - As per Stephen's comments, squashed patch 1 into patch 2, added Fixes tag.
 - As per Akash's comments, included FIFO case in stop_xfer, fixed minor nitpicks.

Changes in V4:
 - As per Stephen's comments cleaned up geni_i2c_stop_xfer function,
   added dma_buf in geni_i2c_dev struct to call i2c_put_dma_safe_msg_buf()
   from other functions, removed "iova" check in geni_se_rx_dma_unprep()
   and geni_se_tx_dma_unprep() functions.
 - Added two helper functions geni_i2c_rx_one_msg_done() and
   geni_i2c_tx_one_msg_done() to unwrap the things after rx/tx FIFO/DMA
   transfers, so that the same can be used in geni_i2c_stop_xfer() function
   during shutdown callback. Updated commit text accordingly.
 - Checking whether it is tx/rx transfer using I2C_M_RD which is valid for both
   FIFO and DMA cases, so dropped DMA_RX_ACTIVE and DMA_TX_ACTIVE bit checking

Changes in V5:
 - As per Stephen's comments, added spin_lock_irqsave & spin_unlock_irqsave in
   geni_i2c_stop_xfer() function.

Changes in V6:
 - As per Stephen's comments, taken care of unsafe lock order in
   geni_i2c_stop_xfer().
 - Moved spin_lock/unlock to geni_i2c_rx_msg_cleanup() and
   geni_i2c_tx_msg_cleanup() functions.

Changes in V7:
 - No changes

Changes in V8:
 - As per Wolfram Sang comment, removed goto and modified geni_i2c_stop_xfer()
   accordingly.

Changes in V9:
 - Fixed possbile race by protecting gi2c->cur and calling geni_i2c_abort_xfer()
   with adding another parameter to differentiate from which sequence is the
   geni_i2c_abort_xfer() called and handle the spin_lock/spin_unlock accordingly
   inside geni_i2c_abort_xfer(). For this added two macros ABORT_XFER and
   STOP_AND_ABORT_XFER.
 - Added a bool variable "stop_xfer" in geni_i2c_dev struct, used to put stop
   to upcoming geni_i2c_rx_one_msg() and geni_i2c_tx_one_msg() calls once we
   recieve the shutdown call.
 - Added gi2c->cur == NULL check in geni_i2c_irq() to not to process the irq
   even if any transfer is queued and shutdown to HW received.

Changes in V10:
 - As per Stephen's comments, removed ongoing transfers flush and only 
   suspending i2c bus in shutdown callback.
 - Also removed all other changes which have been made for ongoing transfers 
   flush, handling race issues etc., during shutdown callback.
 - Updated commit text accordingly.

Changes in V11:
 - As per Stephen's comments, suspended bus in shutdown call using 
   i2c_mark_adapter_suspended() call to block any future transfers.

 drivers/i2c/busses/i2c-qcom-geni.c | 9 +++++++++
 1 file changed, 9 insertions(+)

Comments

Roja Rani Yarubandi May 31, 2021, 5:24 a.m. | #1
On 2021-05-28 13:41, Wolfram Sang wrote:
> On Tue, May 25, 2021 at 06:40:50PM +0530, Roja Rani Yarubandi wrote:

>> If the hardware is still accessing memory after SMMU translation

>> is disabled (as part of smmu shutdown callback), then the

>> IOVAs (I/O virtual address) which it was using will go on the bus

>> as the physical addresses which will result in unknown crashes

>> like NoC/interconnect errors.

>> 

>> So, implement shutdown callback for i2c driver to suspend the bus

>> during system "reboot" or "shutdown".

>> 

>> Fixes: 37692de5d523 ("i2c: i2c-qcom-geni: Add bus driver for the 

>> Qualcomm GENI I2C controller")

>> Signed-off-by: Roja Rani Yarubandi <rojay@codeaurora.org>

> 

> Do we need patch 1 after patch 2 was applied? I always thought all

> devices are suspended before shutdown/reboot?

> 


Yes, both patch 1 and patch 2 are required.
Devices are not suspended during shutdown/reboot.

> Nice to see that 'mark_adapter_suspended' becomes useful again!


Thanks,
Roja
Roja Rani Yarubandi June 2, 2021, 5:07 a.m. | #2
On 2021-05-28 13:41, Wolfram Sang wrote:
> On Tue, May 25, 2021 at 06:40:50PM +0530, Roja Rani Yarubandi wrote:
>> If the hardware is still accessing memory after SMMU translation
>> is disabled (as part of smmu shutdown callback), then the
>> IOVAs (I/O virtual address) which it was using will go on the bus
>> as the physical addresses which will result in unknown crashes
>> like NoC/interconnect errors.
>> 
>> So, implement shutdown callback for i2c driver to suspend the bus
>> during system "reboot" or "shutdown".
>> 
>> Fixes: 37692de5d523 ("i2c: i2c-qcom-geni: Add bus driver for the 
>> Qualcomm GENI I2C controller")
>> Signed-off-by: Roja Rani Yarubandi <rojay@codeaurora.org>
> 
> Do we need patch 1 after patch 2 was applied? I always thought all
> devices are suspended before shutdown/reboot?
> 

Yes, both patch 1 and patch 2 are required.
Devices are not suspended during shutdown/reboot.

> Nice to see that 'mark_adapter_suspended' becomes useful again!

Thanks,
Roja
Wolfram Sang June 4, 2021, 8:33 p.m. | #3
On Tue, May 25, 2021 at 06:40:50PM +0530, Roja Rani Yarubandi wrote:
> If the hardware is still accessing memory after SMMU translation
> is disabled (as part of smmu shutdown callback), then the
> IOVAs (I/O virtual address) which it was using will go on the bus
> as the physical addresses which will result in unknown crashes
> like NoC/interconnect errors.
> 
> So, implement shutdown callback for i2c driver to suspend the bus
> during system "reboot" or "shutdown".
> 
> Fixes: 37692de5d523 ("i2c: i2c-qcom-geni: Add bus driver for the Qualcomm GENI I2C controller")
> Signed-off-by: Roja Rani Yarubandi <rojay@codeaurora.org>

Applied to for-current, thanks!

Patch

diff --git a/drivers/i2c/busses/i2c-qcom-geni.c b/drivers/i2c/busses/i2c-qcom-geni.c
index 214b4c913a13..c3ae66ba6345 100644
--- a/drivers/i2c/busses/i2c-qcom-geni.c
+++ b/drivers/i2c/busses/i2c-qcom-geni.c
@@ -650,6 +650,14 @@  static int geni_i2c_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static void geni_i2c_shutdown(struct platform_device *pdev)
+{
+	struct geni_i2c_dev *gi2c = platform_get_drvdata(pdev);
+
+	/* Make client i2c transfers start failing */
+	i2c_mark_adapter_suspended(&gi2c->adap);
+}
+
 static int __maybe_unused geni_i2c_runtime_suspend(struct device *dev)
 {
 	int ret;
@@ -714,6 +722,7 @@  MODULE_DEVICE_TABLE(of, geni_i2c_dt_match);
 static struct platform_driver geni_i2c_driver = {
 	.probe  = geni_i2c_probe,
 	.remove = geni_i2c_remove,
+	.shutdown = geni_i2c_shutdown,
 	.driver = {
 		.name = "geni_i2c",
 		.pm = &geni_i2c_pm_ops,