drivers/pci/controller/pcie-mediatek-gen3.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
The driver for MediaTek gen3 PCIe hosts de-asserts all reset
signals at the same time using a single register write operation.
Delay the de-assertion of the #PERST signal by 100ms as required by
PCIe CEM clause 2.2, some PCIe devices fail to come up otherwise.
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
---
drivers/pci/controller/pcie-mediatek-gen3.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/controller/pcie-mediatek-gen3.c b/drivers/pci/controller/pcie-mediatek-gen3.c
index e0e27645fdf4..ba8cfce03aad 100644
--- a/drivers/pci/controller/pcie-mediatek-gen3.c
+++ b/drivers/pci/controller/pcie-mediatek-gen3.c
@@ -350,7 +350,13 @@ static int mtk_pcie_startup_port(struct mtk_gen3_pcie *pcie)
msleep(100);
/* De-assert reset signals */
- val &= ~(PCIE_MAC_RSTB | PCIE_PHY_RSTB | PCIE_BRG_RSTB | PCIE_PE_RSTB);
+ val &= ~(PCIE_MAC_RSTB | PCIE_PHY_RSTB | PCIE_BRG_RSTB);
+ writel_relaxed(val, pcie->base + PCIE_RST_CTRL_REG);
+
+ msleep(100);
+
+ /* De-assert PERST# signals */
+ val &= ~(PCIE_PE_RSTB);
writel_relaxed(val, pcie->base + PCIE_RST_CTRL_REG);
/* Check if the link is up or not */
--
2.42.0
On Fri, Oct 06, 2023 at 09:45:58AM +0200, Daniel Golle wrote: > The driver for MediaTek gen3 PCIe hosts de-asserts all reset > signals at the same time using a single register write operation. > Delay the de-assertion of the #PERST signal by 100ms as required by > PCIe CEM clause 2.2, some PCIe devices fail to come up otherwise. > > Signed-off-by: Daniel Golle <daniel@makrotopia.org> > --- > drivers/pci/controller/pcie-mediatek-gen3.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/drivers/pci/controller/pcie-mediatek-gen3.c b/drivers/pci/controller/pcie-mediatek-gen3.c > index e0e27645fdf4..ba8cfce03aad 100644 > --- a/drivers/pci/controller/pcie-mediatek-gen3.c > +++ b/drivers/pci/controller/pcie-mediatek-gen3.c > @@ -350,7 +350,13 @@ static int mtk_pcie_startup_port(struct mtk_gen3_pcie *pcie) I feel like I'm missing something because this patch seems to be adding a delay for T_PVPERL, but the comment before the existing msleep() claims *it* is the T_PVPERL delay: * Described in PCIe CEM specification sections 2.2 (PERST# Signal) * and 2.2.1 (Initial Power-Up (G3 to S0)). * The deassertion of PERST# should be delayed 100ms (TPVPERL) * for the power and clock to become stable. > msleep(100); > > /* De-assert reset signals */ > - val &= ~(PCIE_MAC_RSTB | PCIE_PHY_RSTB | PCIE_BRG_RSTB | PCIE_PE_RSTB); > + val &= ~(PCIE_MAC_RSTB | PCIE_PHY_RSTB | PCIE_BRG_RSTB); > + writel_relaxed(val, pcie->base + PCIE_RST_CTRL_REG); > + > + msleep(100); So I'm confused about these two sleeps. Are they for different parameters? T_PVPERL is defined from "Power stable to PERST# inactive". Do we have any actual indication of when to start that delay, i.e., do we have a clue about when power became stable? > + /* De-assert PERST# signals */ > + val &= ~(PCIE_PE_RSTB); > writel_relaxed(val, pcie->base + PCIE_RST_CTRL_REG); > > /* Check if the link is up or not */ > -- > 2.42.0 > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
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