R: [PATCH v2 07/10] PCIe: qcom: fix init problem with missing PARF programming

From: <ansuelsmth@gmail.com>
To: "'Stanimir Varbanov'" <svarbanov@mm-sol.com>,
	"'Andy Gross'" <agross@kernel.org>
Cc: "'Bjorn Andersson'" <bjorn.andersson@linaro.org>,
	"'Bjorn Helgaas'" <bhelgaas@google.com>,
	"'Rob Herring'" <robh+dt@kernel.org>,
	"'Mark Rutland'" <mark.rutland@arm.com>,
	"'Lorenzo Pieralisi'" <lorenzo.pieralisi@arm.com>,
	"'Andrew Murray'" <amurray@thegoodpenguin.co.uk>,
	"'Philipp Zabel'" <p.zabel@pengutronix.de>,
	<linux-arm-msm@vger.kernel.org>, <linux-pci@vger.kernel.org>,
	<devicetree@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: R: [PATCH v2 07/10] PCIe: qcom: fix init problem with missing PARF programming
Date: Wed, 8 Apr 2020 14:38:21 +0200	[thread overview]
Message-ID: <053e01d60da2$984f1170$c8ed3450$@gmail.com> (raw)
In-Reply-To: <fea9cfd1-2bc7-0141-444e-9c781877ad02@mm-sol.com>

> PARF programming
> 
> Hi Ansuel,
> 
> Please fix the patch subject for all patches in the series per Bjorn H.
> request.
> 
> PCI: qcom: Fix init problem with missing PARF programming
> 
> Also the patch subject is misleading to me. Actually you change few phy
> parameters: Tx De-Emphasis, Tx Swing and Rx equalization. On the other
> side I guess those parameters are board specific and I'm not sure how
> this change will reflect on apq8064 boards.
> 

I also think that this would brake apq8064, on ipq8064 this is needed or 
the system doesn't boot. 
Should I move this to the dts and set this params only if they are present
in dts or also here check for compatible and set accordingly? 

> On 4/2/20 3:11 PM, Ansuel Smith wrote:
> > PARF programming was missing and this cause initilizzation problem on
> > some ipq806x based device (Netgear R7800 for example). This cause a
> > total lock of the system on kernel load.
> >
> > Fixes: 82a82383 PCI: qcom: Add Qualcomm PCIe controller driver
> > Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
> > ---
> >  drivers/pci/controller/dwc/pcie-qcom.c | 48 +++++++++++++++++++++--
> ---
> >  1 file changed, 39 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/pci/controller/dwc/pcie-qcom.c
> b/drivers/pci/controller/dwc/pcie-qcom.c
> > index 211a1aa7d0f1..77b1ab7e23a3 100644
> > --- a/drivers/pci/controller/dwc/pcie-qcom.c
> > +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> > @@ -46,6 +46,9 @@
> >
> >  #define PCIE20_PARF_PHY_CTRL			0x40
> >  #define PCIE20_PARF_PHY_REFCLK			0x4C
> > +#define REF_SSP_EN				BIT(16)
> > +#define REF_USE_PAD				BIT(12)
> 
> Could you rename this to:
> 
> PHY_REFCLK_SSP_EN
> PHY_REFCLK_USE_PAD
> 
> > +
> >  #define PCIE20_PARF_DBI_BASE_ADDR		0x168
> >  #define PCIE20_PARF_SLV_ADDR_SPACE_SIZE		0x16C
> >  #define PCIE20_PARF_MHI_CLOCK_RESET_CTRL	0x174
> > @@ -77,6 +80,18 @@
> >  #define DBI_RO_WR_EN				1
> >
> >  #define PERST_DELAY_US				1000
> > +/* PARF registers */
> > +#define PCIE20_PARF_PCS_DEEMPH			0x34
> > +#define PCS_DEEMPH_TX_DEEMPH_GEN1(x)		(x << 16)
> > +#define PCS_DEEMPH_TX_DEEMPH_GEN2_3_5DB(x)	(x << 8)
> > +#define PCS_DEEMPH_TX_DEEMPH_GEN2_6DB(x)	(x << 0)
> > +
> > +#define PCIE20_PARF_PCS_SWING			0x38
> > +#define PCS_SWING_TX_SWING_FULL(x)		(x << 8)
> > +#define PCS_SWING_TX_SWING_LOW(x)		(x << 0)
> > +
> > +#define PCIE20_PARF_CONFIG_BITS		0x50
> > +#define PHY_RX0_EQ(x)				(x << 24)
> >
> >  #define PCIE20_v3_PARF_SLV_ADDR_SPACE_SIZE	0x358
> >  #define SLV_ADDR_SPACE_SZ			0x10000000
> > @@ -184,6 +199,16 @@ struct qcom_pcie {
> >
> >  #define to_qcom_pcie(x)		dev_get_drvdata((x)->dev)
> >
> > +static inline void qcom_clear_and_set_dword(void __iomem *addr,
> 
> drop 'inline' the compiler is smart enough to decide.
> 
> > +				 u32 clear_mask, u32 set_mask)
> > +{
> > +	u32 val = readl(addr);
> > +
> > +	val &= ~clear_mask;
> > +	val |= set_mask;
> > +	writel(val, addr);
> > +}
> > +
> 
> If you add such function you should introduce it in a separate patch and
> use it in the whole driver where it is applicable. After that we can see
> what is the benefit of it.
> 
> >  static void qcom_ep_reset_assert(struct qcom_pcie *pcie)
> >  {
> >  	gpiod_set_value_cansleep(pcie->reset, 1);
> > @@ -304,7 +329,6 @@ static int qcom_pcie_init_2_1_0(struct
> qcom_pcie *pcie)
> >  	struct qcom_pcie_resources_2_1_0 *res = &pcie->res.v2_1_0;
> >  	struct dw_pcie *pci = pcie->pci;
> >  	struct device *dev = pci->dev;
> > -	u32 val;
> >  	int ret;
> >
> >  	ret = regulator_bulk_enable(ARRAY_SIZE(res->supplies), res-
> >supplies);
> > @@ -355,15 +379,21 @@ static int qcom_pcie_init_2_1_0(struct
> qcom_pcie *pcie)
> >  		goto err_deassert_ahb;
> >  	}
> >
> > -	/* enable PCIe clocks and resets */
> > -	val = readl(pcie->parf + PCIE20_PARF_PHY_CTRL);
> > -	val &= ~BIT(0);
> > -	writel(val, pcie->parf + PCIE20_PARF_PHY_CTRL);
> > +	qcom_clear_and_set_dword(pcie->parf + PCIE20_PARF_PHY_CTRL,
> BIT(0), 0);
> 
> please keep the comment.
> 
> > +
> > +	/* PARF programming */
> 
> pointless comment, please drop it.
> 
> > +	writel(PCS_DEEMPH_TX_DEEMPH_GEN1(0x18) |
> > +	       PCS_DEEMPH_TX_DEEMPH_GEN2_3_5DB(0x18) |
> > +	       PCS_DEEMPH_TX_DEEMPH_GEN2_6DB(0x22),
> > +	       pcie->parf + PCIE20_PARF_PCS_DEEMPH);
> > +	writel(PCS_SWING_TX_SWING_FULL(0x78) |
> > +	       PCS_SWING_TX_SWING_LOW(0x78),
> > +	       pcie->parf + PCIE20_PARF_PCS_SWING);
> > +	writel(PHY_RX0_EQ(0x4), pcie->parf + PCIE20_PARF_CONFIG_BITS);
> >
> > -	/* enable external reference clock */
> > -	val = readl(pcie->parf + PCIE20_PARF_PHY_REFCLK);
> > -	val |= BIT(16);
> > -	writel(val, pcie->parf + PCIE20_PARF_PHY_REFCLK);
> > +	/* enable reference clock */
> 
> Why you dropped 'external' ?
> 
> > +	qcom_clear_and_set_dword(pcie->parf +
> PCIE20_PARF_PHY_REFCLK,
> > +		      REF_USE_PAD, REF_SSP_EN);
> >
> >  	ret = reset_control_deassert(res->phy_reset);
> >  	if (ret) {
> >
> 
> --
> regards,
> Stan