[PATCH] PCI: cadence: Enable support for applying lane equalization presets

[Siddharth Vadapalli]

On Tue, 2025-10-28 at 06:47 -0500, Bjorn Helgaas wrote:

Hello Bjorn,

> On Tue, Oct 28, 2025 at 10:56:33AM +0530, Siddharth Vadapalli wrote:
> > On Tue, 2025-10-28 at 13:16 +0800, kernel test robot wrote:
> > > Hi Siddharth,
> > > 
> > > kernel test robot noticed the following build warnings:
> > > 
> > > [auto build test WARNING on pci/next]
> > > [also build test WARNING on pci/for-linus linus/master v6.18-rc3 next-20251027]
> > > [If your patch is applied to the wrong git tree, kindly drop us a note.
> > > And when submitting patch, we suggest to use '--base' as documented in
> > > https://git-scm.com/docs/git-format-patch#_base_tree_information]
> > > 
> > > url:    https://github.com/intel-lab-lkp/linux/commits/Siddharth-Vadapalli/PCI-cadence-Enable-support-for-applying-lane-equalization-presets/20251027-213657
> > > base:   https://git.kernel.org/pub/scm/linux/kernel/git/pci/pci.git next
> > > patch link:    https://lore.kernel.org/r/20251027133013.2589119-1-s-vadapalli%40ti.com
> > > patch subject: [PATCH] PCI: cadence: Enable support for applying lane equalization presets
> > > config: x86_64-buildonly-randconfig-002-20251028 (https://download.01.org/0day-ci/archive/20251028/202510281329.racaZPSI-lkp@intel.com/config)
> > > compiler: gcc-14 (Debian 14.2.0-19) 14.2.0
> > > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251028/202510281329.racaZPSI-lkp@intel.com/reproduce)
> > > 
> > > If you fix the issue in a separate patch/commit (i.e. not just a new version of
> > > the same patch/commit), kindly add following tags
> > > > Reported-by: kernel test robot <lkp at intel.com>
> > > > Closes: https://lore.kernel.org/oe-kbuild-all/202510281329.racaZPSI-lkp@intel.com/
> > > 
> > > All warnings (new ones prefixed by >>):
> > > 
> > >    drivers/pci/controller/cadence/pcie-cadence-host.c: In function 'cdns_pcie_setup_lane_equalization_presets':
> > > > > drivers/pci/controller/cadence/pcie-cadence-host.c:205:20: warning: this statement may fall through [-Wimplicit-fallthrough=]
> > >      205 |                 if (presets_ngts[0] != PCI_EQ_RESV) {
> > >          |                    ^
> > >    drivers/pci/controller/cadence/pcie-cadence-host.c:225:9: note: here
> > >      225 |         case PCIE_SPEED_8_0GT:
> > >          |         ^~~~
> > 
> > Fallthrough is intentional. The lane equalization presets are programmed
> > starting from the Max Supported Link speed and we fallthrough until we get
> > to 8.0 GT/s.
> 
> It's poorly documented, but use "fallthrough" here:
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/deprecated.rst?id=v6.17#n200

Thank you for pointing me to the documentation. I will update the patch
accordingly and post the v2 patch.

Regards,
Siddharth.