5.4-stable review patch. If anyone has any objections, please let me know.
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From: Andrew Halaney ahalaney@redhat.com
[ Upstream commit e4a628877119bd40164a651d20321247b6f94a8b ]
Currently, interrupts are cleared and disabled prior to registering the interrupt. An mb() is used to complete the clear/disable writes before the interrupt is registered.
mb() ensures that the write completes, but completion doesn't mean that it isn't stored in a buffer somewhere. The recommendation for ensuring these bits have taken effect on the device is to perform a read back to force it to make it all the way to the device. This is documented in device-io.rst and a talk by Will Deacon on this can be seen over here:
https://youtu.be/i6DayghhA8Q?si=MiyxB5cKJXSaoc01&t=1678
Let's do that to ensure these bits hit the device. Because the mb()'s purpose wasn't to add extra ordering (on top of the ordering guaranteed by writel()/readl()), it can safely be removed.
Fixes: 199ef13cac7d ("scsi: ufs: avoid spurious UFS host controller interrupts") Reviewed-by: Manivannan Sadhasivam manivannan.sadhasivam@linaro.org Reviewed-by: Bart Van Assche bvanassche@acm.org Reviewed-by: Can Guo quic_cang@quicinc.com Signed-off-by: Andrew Halaney ahalaney@redhat.com Link: https://lore.kernel.org/r/20240329-ufs-reset-ensure-effect-before-delay-v5-8... Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/scsi/ufs/ufshcd.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c index 363adf489079a..ea6148ee27835 100644 --- a/drivers/scsi/ufs/ufshcd.c +++ b/drivers/scsi/ufs/ufshcd.c @@ -8424,7 +8424,7 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq) * Make sure that UFS interrupts are disabled and any pending interrupt * status is cleared before registering UFS interrupt handler. */ - mb(); + ufshcd_readl(hba, REG_INTERRUPT_ENABLE);
/* IRQ registration */ err = devm_request_irq(dev, irq, ufshcd_intr, IRQF_SHARED, UFSHCD, hba);