[Linux-kernel-mentees] [RFC PATCH 01/17] ata: Drop uses of pci_read_config_*() return value

Saheed O. Bolarinwa refactormyself at gmail.com
Sat Aug 1 11:24:30 UTC 2020

The return value of pci_read_config_*() may not indicate a device error.
However, the value read by these functions is more likely to indicate
this kind of error. This presents two overlapping ways of reporting
errors and complicates error checking.

It is possible to move to one single way of checking for error if the
dependency on the return value of these functions is removed, then it
can later be made to return void.

Remove all uses of the return value of pci_read_config_*().
Check the actual value read for ~0. In this case, ~0 is an invalid value
thus it indicates some kind of error.

drivers/ata/pata_cs5536.c cs5536_read() :
None of the callers of cs5536_read() uses the return value. The obtained
value can be checked for validity to confirm success.

Change the return type of cs5536_read() to void.

Suggested-by: Bjorn Helgaas <bjorn at helgaas.com>
Signed-off-by: Saheed O. Bolarinwa <refactormyself at gmail.com>
 drivers/ata/pata_cs5536.c | 6 +++---
 drivers/ata/pata_rz1000.c | 3 ++-
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/ata/pata_cs5536.c b/drivers/ata/pata_cs5536.c
index 760ac6e65216..c204215e239f 100644
--- a/drivers/ata/pata_cs5536.c
+++ b/drivers/ata/pata_cs5536.c
@@ -83,16 +83,16 @@ static const struct dmi_system_id udma_quirk_dmi_table[] = {
 	{ }
-static int cs5536_read(struct pci_dev *pdev, int reg, u32 *val)
+static void cs5536_read(struct pci_dev *pdev, int reg, u32 *val)
 	if (unlikely(use_msr)) {
 		u32 dummy __maybe_unused;
 		rdmsr(MSR_IDE_CFG + reg, *val, dummy);
-		return 0;
+		return;
-	return pci_read_config_dword(pdev, PCI_IDE_CFG + reg * 4, val);
+	pci_read_config_dword(pdev, PCI_IDE_CFG + reg * 4, val);
 static int cs5536_write(struct pci_dev *pdev, int reg, int val)
diff --git a/drivers/ata/pata_rz1000.c b/drivers/ata/pata_rz1000.c
index 3722a67083fd..e0b3de376357 100644
--- a/drivers/ata/pata_rz1000.c
+++ b/drivers/ata/pata_rz1000.c
@@ -64,7 +64,8 @@ static int rz1000_fifo_disable(struct pci_dev *pdev)
 	u16 reg;
 	/* Be exceptionally paranoid as we must be sure to apply the fix */
-	if (pci_read_config_word(pdev, 0x40, &reg) != 0)
+	pci_read_config_word(pdev, 0x40, &reg);
+	if (reg == (u16)~0)
 		return -1;
 	reg &= 0xDFFF;
 	if (pci_write_config_word(pdev, 0x40, reg) != 0)

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