phy: qcom: qmp-pcie: Fix PHY initialization when powered down by firmware
Commit 0cc22f5a861c ("phy: qcom: qmp-pcie: Add PHY register retention
support") added support for using the "no_csr" reset to skip configuration
of the PHY if the init sequence was already applied by the boot firmware.
The expectation is that the PHY is only turned on/off by using the "no_csr"
reset, instead of powering it down and re-programming it after a full
reset.
The boot firmware on X1E does not fully conform to this expectation: If the
PCIe3 link fails to come up (e.g. because no PCIe card is inserted), the
firmware powers down the PHY using the QPHY_PCS_POWER_DOWN_CONTROL
register. The QPHY_START_CTRL register is kept as-is, so the driver assumes
the PHY is already initialized and skips the configuration/power up
sequence. The PHY won't come up again without clearing the
QPHY_PCS_POWER_DOWN_CONTROL, so eventually initialization fails:
qcom-qmp-pcie-phy 1be0000.phy: phy initialization timed-out
phy phy-1be0000.phy.0: phy poweron failed --> -110
qcom-pcie 1bd0000.pcie: cannot initialize host
qcom-pcie 1bd0000.pcie: probe with driver qcom-pcie failed with error -110
This can be reliably reproduced on the X1E CRD, QCP and Devkit when no card
is inserted for PCIe3.
Fix this by checking the QPHY_PCS_POWER_DOWN_CONTROL register in addition
to QPHY_START_CTRL. If the PHY is powered down with the register, it
doesn't conform to the expectations for using the "no_csr" reset, so we
fully re-initialize with the normal reset sequence.
Also check the register more carefully to ensure all of the bits we expect
are actually set. A simple !!(readl()) is not enough, because the PHY might
be only partially set up with some of the expected bits set.
Cc: stable@vger.kernel.org
Fixes: 0cc22f5a861c ("phy: qcom: qmp-pcie: Add PHY register retention support")
Signed-off-by: Stephan Gerhold <stephan.gerhold@linaro.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20250821-phy-qcom-qmp-pcie-nocsr-fix-v3-1-4898db0cc07c@linaro.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>
1 file changed
