[PATCHv4 3/4] ata: sata_dwc_460ex: fix clear_interrupt_bit() clearing all pending interrupts

[Rosen Penev]

clear_interrupt_bit() ignores the bit argument and performs a
read-write-back of the entire INTPR register.  If INTPR uses standard
Write-1-to-Clear semantics, this clears every pending interrupt bit,
not just the intended one.  Coalesced interrupts (e.g. DMAT + NEWFP)
would be cleared together, silently losing the second event.

Write only the specific bit to clear so that other pending interrupts
are preserved.

Fixes: 62936009f35a ("[libata] Add 460EX on-chip SATA driver, sata_dwc_460ex")
Assisted-by: opencode:big-pickle
Signed-off-by: Rosen Penev <rosenp@xxxxxxxxx>
---
 drivers/ata/sata_dwc_460ex.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/ata/sata_dwc_460ex.c b/drivers/ata/sata_dwc_460ex.c
index 85c5e67e9175..bc543a408963 100644
--- a/drivers/ata/sata_dwc_460ex.c
+++ b/drivers/ata/sata_dwc_460ex.c
@@ -394,8 +394,7 @@ static void clear_serror(struct ata_port *ap)
 
 static void clear_interrupt_bit(struct sata_dwc_device *hsdev, u32 bit)
 {
-	sata_dwc_writel(&hsdev->sata_dwc_regs->intpr,
-			sata_dwc_readl(&hsdev->sata_dwc_regs->intpr));
+	sata_dwc_writel(&hsdev->sata_dwc_regs->intpr, bit);
 }
 
 static u32 qcmd_tag_to_mask(u8 tag)
-- 
2.55.0