On Fri, Jul 08, 2022 at 02:17:09PM -0500, Bjorn Helgaas wrote: > On Fri, Jul 08, 2022 at 07:02:48PM +0200, Christian Marangi wrote: > > On Fri, Jul 08, 2022 at 06:47:57PM +0200, Christian Marangi wrote: > > > On Fri, Jul 08, 2022 at 06:39:37PM +0200, Robert Marko wrote: > > > > On Thu, 7 Jul 2022 at 21:41, Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote: > > > > > On Fri, Jun 24, 2022 at 12:44:20PM +0200, Robert Marko wrote: > > > > > > IPQ8074 requires the PHY to be powered on before accessing DBI registers. > > > > > > It's not clear whether other variants have the same dependency, but there > > > > > > seems to be no reason for them to be different, so move all the DBI > > > > > > accesses from .init() to .post_init() so they are all after phy_power_on(). > > > > > > > > > > > > Signed-off-by: Robert Marko <robimarko@xxxxxxxxx> > > > > > > > > > > Would any of the qcom driver folks care to review and ack this? > > > > > Stanimir, Andy, Bjorn A (from get_maintainer.pl)? > > > > > > Hi Bjorn, > > > I tested this on ipq806x and the current patch cause regression as pci > > > doesn't work anymore... > > > This is a before the patch [1] and this is an after [2]. > > > > > > As you notice the main problem here is > > > [ 2.559962] qcom-pcie 1b700000.pci: Phy link never came up > > > > > > The cause of this has already been bisected and actually it was a fixup > > > pushed some time ago for 2_1_0. > > > > > > Uboot can leave the pci in an underfined state and this > > > writel(1, pcie->parf + PCIE20_PARF_PHY_CTRL); > > > is never called. > > > > > > This is mandatory to a correct init and MUST be called before regulator > > > enable and reset deassert or the "Phy link never came up" problem is > > > triggered. > > > > > > So to fix this we just have to have > > > writel(1, pcie->parf + PCIE20_PARF_PHY_CTRL); > > > in qcom_pcie_init_2_1_0 right after the reset_contro_assert. > > > > > > This command is also present in qcom_pcie_init_2_3_2 where the same > > > exact reg is written so I assume 2_3_2 have the same regression and the > > > write must be placed in init and can't be moved to post_init. > > > > > > Feel free to tell me how to proceed if I should post an additional patch > > > or you prefer Robi to respin this with the few lines reverted. > > > > > > [1] https://gist.github.com/Ansuel/ec827319e585630356fc586273db6f0d > > > [2] https://gist.github.com/Ansuel/63fbcab2681cd28a61ec52d7874fa30d > > > > While testing this I notice something odd... > > > > 2_4_2 prepare the pipe clock only AFTER PCIe clocks and reset are > > enabled while in 2_1_0... That made me think there could be a problem > > with the current code of 2_1_0... A quick change made me discover that > > the problem is actually that we enable prepare_enable clock BEFORE the > > value is written in PCIE20_PARF_PHY_CTRL. > > > > By moving the clk_bulk_prepare_enable after the "enable PCIe clocks and > > resets" make the pci work with the current change... > > > > So it could be that the current changes are correct and it's really just > > a bug in 2_1_0 enabling clock before writing the correct value... > > > > Tell me how to proceed... think at this point a good idea would be to > > create a separate patch and fix this for good. > > Hmm, I think I made a mistake when I put this patch in the middle and > applied other stuff on top of it. I'd like to just postpone this > patch while we work out these issues, but I think it's not completely > trivial since it's in the middle. I'll try to straighten this out > next week. > >From my discoveries it really seems just a bug in 2_1_0 with enabling the phy clk BEFORE setting the require bit... Moving the bulk_prepare_enable after the bit is set makes everything works as it should... If you want I can send a patch as that is clearly a bug and currenty we have a workaround in place... (with the patch the workaround can be dropped aka we even remove a line of code) > > Also bonus question, should I drop the bulk_prepare_enable and follow > > the pattern of 2_3_2 and enable aux, cfg, master and slave in init and > > pipe in post init or I can keep it? (still have to test but I assume > > that it will work.) > > I haven't looked at the code again, but will just offer the opinion > that unnecessary differences in structure often hide bugs, and they're > always minor speed bumps for readers. > > Bjorn Considering it won't change anything and pci 2_1_0 use the bulk api... calling each clock separately will actually makes things less readable... Sooo think it's just a line to drop and a code move. -- Ansuel
