Re: [PATCH v4 0/6] PCI: dwc: Rework the error handling of dw_pcie_wait_for_link() API

[Manivannan Sadhasivam]

On Tue, Oct 13, 2026 at 11:15:28AM +0200, Franz Schnyder wrote:
> On Wed, Jan 07, 2026 at 01:41:53PM +0530, Manivannan Sadhasivam via B4 Relay wrote:
> > Hi,
> > 
> > This series reworks the dw_pcie_wait_for_link() API to allow the callers to
> > detect the absence of the device on the bus and skip the failure.
> > 
> > Compared to v2, I've reworked the patch 2 to improve the API further and
> > dropped the patch 1 that got applied (hence changed the subject). I've also
> > modified the error code based on the feedback in v2 to return -ENODEV if device
> > is not detected on the bus and -ETIMEDOUT otherwise. This allows the callers to
> > skip the failure if device is not detected and handle error for other failure.
> > 
> > Testing
> > =======
> > 
> > Tested this series on Rb3Gen2 board without powering on the PCIe switch. Now the
> > dw_pcie_wait_for_link() API prints:
> > 
> > 	qcom-pcie 1c08000.pcie: Device not found
> > 
> > Instead of the previous log:
> > 
> > 	qcom-pcie 1c08000.pcie: Phy link never came up
> > 
> > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxxxxxxxx>
> > ---
> > Changes in v4:
> > - Skipped returning failure during resume as well if no device is found
> > - Link to v3: https://lore.kernel.org/r/20251230-pci-dwc-suspend-rework-v3-0-40cd485714f5@xxxxxxxxxxxxxxxx
> > 
> > Changes in v3:
> > - Dropped patch 1 that got appplied
> > - Reworked the error handling of dw_pcie_wait_for_link() API further
> > - Link to v2: https://lore.kernel.org/r/20251218-pci-dwc-suspend-rework-v2-0-5a7778c6094a@xxxxxxxxxxxxxxxx
> > 
> > Changes in v2:
> > - Changed the logic to check for Detect.Quiet/Active states
> > - Collected tags and rebased on top of v6.19-rc1
> > - Link to v1: https://lore.kernel.org/r/20251119-pci-dwc-suspend-rework-v1-0-aad104828562@xxxxxxxxxxxxxxxx
> > 
> > ---
> > Manivannan Sadhasivam (6):
> >       PCI: dwc: Return -ENODEV from dw_pcie_wait_for_link() if device is not found
> >       PCI: dwc: Rename and move ltssm_status_string() to pcie-designware.c
> >       PCI: dwc: Rework the error print of dw_pcie_wait_for_link()
> >       PCI: dwc: Only skip the dw_pcie_wait_for_link() failure if it returns -ENODEV
> >       PCI: host-common: Add an API to check for any device under the Root Ports
> >       PCI: dwc: Skip failure during dw_pcie_resume_noirq() if no device is available
> > 
> >  .../pci/controller/dwc/pcie-designware-debugfs.c   | 54 +---------------
> >  drivers/pci/controller/dwc/pcie-designware-host.c  | 23 +++++--
> >  drivers/pci/controller/dwc/pcie-designware.c       | 75 +++++++++++++++++++++-
> >  drivers/pci/controller/dwc/pcie-designware.h       |  2 +
> >  drivers/pci/controller/pci-host-common.c           | 21 ++++++
> >  drivers/pci/controller/pci-host-common.h           |  2 +
> >  6 files changed, 115 insertions(+), 62 deletions(-)
> > ---
> > base-commit: 68ac85fb42cfeb081cf029acdd8aace55ed375a2
> > change-id: 20251119-pci-dwc-suspend-rework-8b0515a38679
> > 
> > Best regards,
> > -- 
> > Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxxxxxxxx>
> > 
> 
> Hi Mani,
> 
> Is there any reason patches 5 and 6 were never applied?
> 

Bjorn had concerns about patch 6 as it didn't handle the case where a device can
get attached during suspend. So I dropped patches 5 and 6. Too bad that I didn't
mention this reasoning in LKML, sorry about that.

- Mani

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