[PATCH] PCI: qcom: Enable clocks only after PARF_PHY setup for rev 2.1.0

[PATCH] PCI: qcom: Enable clocks only after PARF_PHY setup for rev 2.1.0

[Christian Marangi]

We currently enable clocks BEFORE we write to PARF_PHY_CTRL reg to
enable clocks and resets. This case the driver to never set to a ready
state with the error 'Phy link never came up'.

This in fact is caused by the phy clock getting enabled before setting
the required bits in the PARF regs.

A workaround for this was set but with this new discovery we can drop
the workaround and use a proper solution to the problem by just enabling
the clock only AFTER the PARF_PHY_CTRL bit is set.

This correctly setup the pcie line and makes it usable even when a
bootloader leave the pcie line to a underfined state.

Fixes: 82a823833f4e ("PCI: qcom: Add Qualcomm PCIe controller driver")
Cc: stable@vger.kernel.org # v5.4+
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
---
 drivers/pci/controller/dwc/pcie-qcom.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index 2ea13750b492..da13a66ced14 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -337,8 +337,6 @@ static int qcom_pcie_init_2_1_0(struct qcom_pcie *pcie)
 	reset_control_assert(res->ext_reset);
 	reset_control_assert(res->phy_reset);
 
-	writel(1, pcie->parf + PCIE20_PARF_PHY_CTRL);
-
 	ret = regulator_bulk_enable(ARRAY_SIZE(res->supplies), res->supplies);
 	if (ret < 0) {
 		dev_err(dev, "cannot enable regulators\n");
@@ -381,15 +379,15 @@ static int qcom_pcie_init_2_1_0(struct qcom_pcie *pcie)
 		goto err_deassert_axi;
 	}
 
-	ret = clk_bulk_prepare_enable(ARRAY_SIZE(res->clks), res->clks);
-	if (ret)
-		goto err_clks;
-
 	/* enable PCIe clocks and resets */
 	val = readl(pcie->parf + PCIE20_PARF_PHY_CTRL);
 	val &= ~BIT(0);
 	writel(val, pcie->parf + PCIE20_PARF_PHY_CTRL);
 
+	ret = clk_bulk_prepare_enable(ARRAY_SIZE(res->clks), res->clks);
+	if (ret)
+		goto err_clks;
+
 	if (of_device_is_compatible(node, "qcom,pcie-ipq8064") ||
 	    of_device_is_compatible(node, "qcom,pcie-ipq8064-v2")) {
 		writel(PCS_DEEMPH_TX_DEEMPH_GEN1(24) |
-- 
2.36.1

Re: [PATCH] PCI: qcom: Enable clocks only after PARF_PHY setup for rev 2.1.0

[Bjorn Helgaas]

On Sat, Jul 09, 2022 at 12:27:43AM +0200, Christian Marangi wrote:
> We currently enable clocks BEFORE we write to PARF_PHY_CTRL reg to
> enable clocks and resets. This case the driver to never set to a ready
> state with the error 'Phy link never came up'.
> 
> This in fact is caused by the phy clock getting enabled before setting
> the required bits in the PARF regs.
> 
> A workaround for this was set but with this new discovery we can drop
> the workaround and use a proper solution to the problem by just enabling
> the clock only AFTER the PARF_PHY_CTRL bit is set.
> 
> This correctly setup the pcie line and makes it usable even when a
> bootloader leave the pcie line to a underfined state.

Is "pcie" here a signal name?  Maybe this refers to the "PCIe link"?

> Fixes: 82a823833f4e ("PCI: qcom: Add Qualcomm PCIe controller driver")
> Cc: stable@vger.kernel.org # v5.4+
> Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>

Thanks, I put this on
https://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git,
pci/ctrl/qcom-pending branch (head 47b4ec9d2e60).

Can you take a look and make sure I didn't mess up the conflict
resolution with the rest of the series?

> ---
>  drivers/pci/controller/dwc/pcie-qcom.c | 10 ++++------
>  1 file changed, 4 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
> index 2ea13750b492..da13a66ced14 100644
> --- a/drivers/pci/controller/dwc/pcie-qcom.c
> +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> @@ -337,8 +337,6 @@ static int qcom_pcie_init_2_1_0(struct qcom_pcie *pcie)
>  	reset_control_assert(res->ext_reset);
>  	reset_control_assert(res->phy_reset);
>  
> -	writel(1, pcie->parf + PCIE20_PARF_PHY_CTRL);
> -
>  	ret = regulator_bulk_enable(ARRAY_SIZE(res->supplies), res->supplies);
>  	if (ret < 0) {
>  		dev_err(dev, "cannot enable regulators\n");
> @@ -381,15 +379,15 @@ static int qcom_pcie_init_2_1_0(struct qcom_pcie *pcie)
>  		goto err_deassert_axi;
>  	}
>  
> -	ret = clk_bulk_prepare_enable(ARRAY_SIZE(res->clks), res->clks);
> -	if (ret)
> -		goto err_clks;
> -
>  	/* enable PCIe clocks and resets */
>  	val = readl(pcie->parf + PCIE20_PARF_PHY_CTRL);
>  	val &= ~BIT(0);
>  	writel(val, pcie->parf + PCIE20_PARF_PHY_CTRL);
>  
> +	ret = clk_bulk_prepare_enable(ARRAY_SIZE(res->clks), res->clks);
> +	if (ret)
> +		goto err_clks;
> +
>  	if (of_device_is_compatible(node, "qcom,pcie-ipq8064") ||
>  	    of_device_is_compatible(node, "qcom,pcie-ipq8064-v2")) {
>  		writel(PCS_DEEMPH_TX_DEEMPH_GEN1(24) |
> -- 
> 2.36.1
> 

Re: [PATCH] PCI: qcom: Enable clocks only after PARF_PHY setup for rev 2.1.0

[Christian Marangi]

On Fri, Jul 08, 2022 at 06:01:55PM -0500, Bjorn Helgaas wrote:
> On Sat, Jul 09, 2022 at 12:27:43AM +0200, Christian Marangi wrote:
> > We currently enable clocks BEFORE we write to PARF_PHY_CTRL reg to
> > enable clocks and resets. This case the driver to never set to a ready
> > state with the error 'Phy link never came up'.
> > 
> > This in fact is caused by the phy clock getting enabled before setting
> > the required bits in the PARF regs.
> > 
> > A workaround for this was set but with this new discovery we can drop
> > the workaround and use a proper solution to the problem by just enabling
> > the clock only AFTER the PARF_PHY_CTRL bit is set.
> > 
> > This correctly setup the pcie line and makes it usable even when a
> > bootloader leave the pcie line to a underfined state.
> 
> Is "pcie" here a signal name?  Maybe this refers to the "PCIe link"?
>

Hi,
no i was referring to PCIe link. Fell free to fix it if it's not a
problem (or if you want i can just resend)

> > Fixes: 82a823833f4e ("PCI: qcom: Add Qualcomm PCIe controller driver")
> > Cc: stable@vger.kernel.org # v5.4+
> > Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
> 
> Thanks, I put this on
> https://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git,
> pci/ctrl/qcom-pending branch (head 47b4ec9d2e60).
> 
> Can you take a look and make sure I didn't mess up the conflict
> resolution with the rest of the series?

Think something went wrong in the rebase as the patch fixup is reverted.

11946f8b6e77a6794c111aafef7772e9967d9a54 is still wrong.

clk_bulk_prepare_enable must be after 
writel(val, pcie->parf + PCIE20_PARF_PHY_CTRL);
so in the post init.

> 
> > ---
> >  drivers/pci/controller/dwc/pcie-qcom.c | 10 ++++------
> >  1 file changed, 4 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
> > index 2ea13750b492..da13a66ced14 100644
> > --- a/drivers/pci/controller/dwc/pcie-qcom.c
> > +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> > @@ -337,8 +337,6 @@ static int qcom_pcie_init_2_1_0(struct qcom_pcie *pcie)
> >  	reset_control_assert(res->ext_reset);
> >  	reset_control_assert(res->phy_reset);
> >  
> > -	writel(1, pcie->parf + PCIE20_PARF_PHY_CTRL);
> > -
> >  	ret = regulator_bulk_enable(ARRAY_SIZE(res->supplies), res->supplies);
> >  	if (ret < 0) {
> >  		dev_err(dev, "cannot enable regulators\n");
> > @@ -381,15 +379,15 @@ static int qcom_pcie_init_2_1_0(struct qcom_pcie *pcie)
> >  		goto err_deassert_axi;
> >  	}
> >  
> > -	ret = clk_bulk_prepare_enable(ARRAY_SIZE(res->clks), res->clks);
> > -	if (ret)
> > -		goto err_clks;
> > -
> >  	/* enable PCIe clocks and resets */
> >  	val = readl(pcie->parf + PCIE20_PARF_PHY_CTRL);
> >  	val &= ~BIT(0);
> >  	writel(val, pcie->parf + PCIE20_PARF_PHY_CTRL);
> >  
> > +	ret = clk_bulk_prepare_enable(ARRAY_SIZE(res->clks), res->clks);
> > +	if (ret)
> > +		goto err_clks;
> > +
> >  	if (of_device_is_compatible(node, "qcom,pcie-ipq8064") ||
> >  	    of_device_is_compatible(node, "qcom,pcie-ipq8064-v2")) {
> >  		writel(PCS_DEEMPH_TX_DEEMPH_GEN1(24) |
> > -- 
> > 2.36.1
> > 

-- 
	Ansuel