[PATCH v3 6/9] PCI/PM: Clean up pci_set_low_power_state()

From: Rafael J. Wysocki
Date: Thu Apr 14 2022 - 09:32:22 EST


From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>

Make the following assorted non-essential changes in
pci_set_low_power_state():

1. Drop two redundant checks from it (the caller takes care of these
conditions).

2. Modify error messages printed by it to make them more consistent
with the messages printed by pci_power_up() and
pci_set_full_power_state().

3. Change the log level of one of the messages to "debug", because
it only indicates a programming mistake.

4. Make it return -ENODEV (instead of -EIO) when the device is not
accessible.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Reviewed-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
---

v1 -> v3:
* Added R-by from Mika.

---
drivers/pci/pci.c | 13 +++----------
1 file changed, 3 insertions(+), 10 deletions(-)

Index: linux-pm/drivers/pci/pci.c
===================================================================
--- linux-pm.orig/drivers/pci/pci.c
+++ linux-pm/drivers/pci/pci.c
@@ -1345,16 +1345,9 @@ static int pci_set_low_power_state(struc
{
u16 pmcsr;

- /* Check if we're already there */
- if (dev->current_state == state)
- return 0;
-
if (!dev->pm_cap)
return -EIO;

- if (state < PCI_D1 || state > PCI_D3hot)
- return -EINVAL;
-
/*
* Validate transition: We can enter D0 from any state, but if
* we're already in a low-power state, we can only go deeper. E.g.,
@@ -1362,7 +1355,7 @@ static int pci_set_low_power_state(struc
* we'd have to go from D3 to D0, then to D1.
*/
if (dev->current_state <= PCI_D3cold && dev->current_state > state) {
- pci_err(dev, "invalid power transition (from %s to %s)\n",
+ pci_dbg(dev, "Invalid power transition (from %s to %s)\n",
pci_power_name(dev->current_state),
pci_power_name(state));
return -EINVAL;
@@ -1375,10 +1368,10 @@ static int pci_set_low_power_state(struc

pci_read_config_word(dev, dev->pm_cap + PCI_PM_CTRL, &pmcsr);
if (PCI_POSSIBLE_ERROR(pmcsr)) {
- pci_err(dev, "can't change power state from %s to %s (config space inaccessible)\n",
+ pci_err(dev, "Unable to change power state from %s to %s, device inaccessible\n",
pci_power_name(dev->current_state),
pci_power_name(state));
- return -EIO;
+ return -ENODEV;
}

pmcsr &= ~PCI_PM_CTRL_STATE_MASK;