Re: [PATCH v3 19/19] PCI: qcom: Expose link transition counts via debugfs for v2.4.0

[Sricharan Ramabadhran]

On 3/14/2023 4:06 PM, Sricharan Ramabadhran wrote:
> On 3/10/2023 9:38 AM, Manivannan Sadhasivam wrote:
> > Qualcomm PCIe controllers of version v2.4.0 have debug registers in the
> > PARF region that count PCIe link transitions. Expose them over debugfs to
> > userspace to help debug the low power issues.
> >
> > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
> > ---
> >   drivers/pci/controller/dwc/pcie-qcom.c | 33 ++++++++++++++++++++++++++
> >   1 file changed, 33 insertions(+)
> >
> > diff --git a/drivers/pci/controller/dwc/pcie-qcom.c 
> > b/drivers/pci/controller/dwc/pcie-qcom.c
> > index f99b7e7f3f73..0b41f007fa90 100644
> > --- a/drivers/pci/controller/dwc/pcie-qcom.c
> > +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> > @@ -37,6 +37,7 @@
> >   /* PARF registers */
> >   #define PARF_SYS_CTRL                0x00
> >   #define PARF_PM_CTRL                0x20
> > +#define PARF_PM_STTS                0x24
> >   #define PARF_PCS_DEEMPH                0x34
> >   #define PARF_PCS_SWING                0x38
> >   #define PARF_PHY_CTRL                0x40
> > @@ -84,6 +85,12 @@
> >   /* PARF_PM_CTRL register fields */
> >   #define REQ_NOT_ENTR_L1                BIT(5)
> > +/* PARF_PM_STTS register fields */
> > +#define PM_LINKST_IN_L1SUB            BIT(8)
> > +#define PM_LINKST_IN_L0S            BIT(7)
> > +#define PM_LINKST_IN_L2                BIT(5)
> > +#define PM_LINKST_IN_L1                BIT(4)
> > +
> >   /* PARF_PCS_DEEMPH register fields */
> >   #define PCS_DEEMPH_TX_DEEMPH_GEN1(x)        FIELD_PREP(GENMASK(21, 
> > 16), x)
> >   #define PCS_DEEMPH_TX_DEEMPH_GEN2_3_5DB(x)    FIELD_PREP(GENMASK(13, 
> > 8), x)
> > @@ -737,6 +744,31 @@ static int qcom_pcie_post_init_2_4_0(struct 
> > qcom_pcie *pcie)
> >       return 0;
> >   }
> > +static int qcom_pcie_debugfs_func_2_4_0(struct seq_file *s, void *data)
> > +{
> > +    struct qcom_pcie *pcie = (struct qcom_pcie *) 
> > dev_get_drvdata(s->private);
> > +
> > +    seq_printf(s, "L0s transition count: %u\n",
> > +           readl_relaxed(pcie->parf + PM_LINKST_IN_L0S));
> > +
> > +    seq_printf(s, "L1 transition count: %u\n",
> > +           readl_relaxed(pcie->parf + PM_LINKST_IN_L1));
> > +
> > +    seq_printf(s, "L1.1 transition count: %u\n",
> > +           readl_relaxed(pcie->parf + PM_LINKST_IN_L1SUB));
> > +
> > +    seq_printf(s, "L2 transition count: %u\n",
> > +           readl_relaxed(pcie->parf + PM_LINKST_IN_L2));
> > +
>
>   Using bitmask as register offset ? instead use PM_STTS and bitmask it ?

 Also, since its 1 bit, all are status and not count.
 Not sure, if you want it to limit this debug based on 'mhi' property
 being populated ?

Regards,
 Sricharan