Re: [PATCH v5 2/2] phy: qcom: qmp-pcie: Add PHY register retention support

[Wenbin Yao (Consultant)]

On 3/14/2025 10:50 PM, Manivannan Sadhasivam wrote:
> On Wed, Feb 26, 2025 at 06:36:00PM +0800, Wenbin Yao wrote:
> > From: Qiang Yu <quic_qianyu@xxxxxxxxxxx>
> >
> > Some QCOM PCIe PHYs support no_csr reset. Unlike BCR reset which resets the
> > whole PHY (hardware and register), no_csr reset only resets PHY hardware
> > but retains register values, which means PHY setting can be skipped during
> > PHY init if PCIe link is enabled in booltloader and only no_csr is toggled
> > after that.
> >
> > Hence, determine whether the PHY has been enabled in bootloader by
> > verifying QPHY_START_CTRL register. If it's programmed and no_csr reset is
> > available, skip BCR reset and PHY register setting to establish the PCIe
> > link with bootloader - programmed PHY settings.
> >
> > Signed-off-by: Qiang Yu <quic_qianyu@xxxxxxxxxxx>
> > Signed-off-by: Wenbin Yao <quic_wenbyao@xxxxxxxxxxx>
> Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
>
> One nit below.
>
> > ---
> >   drivers/phy/qualcomm/phy-qcom-qmp-pcie.c | 69 ++++++++++++++++++++----
> >   1 file changed, 59 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c b/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c
> > index 219266125cf2..c3642d1807e4 100644
> > --- a/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c
> > +++ b/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c
> > @@ -2805,6 +2805,7 @@ struct qmp_pcie {
> >   
> >   	const struct qmp_phy_cfg *cfg;
> >   	bool tcsr_4ln_config;
> > +	bool skip_init;
> >   
> >   	void __iomem *serdes;
> >   	void __iomem *pcs;
> > @@ -3976,18 +3977,38 @@ static int qmp_pcie_init(struct phy *phy)
> >   {
> >   	struct qmp_pcie *qmp = phy_get_drvdata(phy);
> >   	const struct qmp_phy_cfg *cfg = qmp->cfg;
> > +	void __iomem *pcs = qmp->pcs;
> > +	bool phy_initialized = !!(readl(pcs + cfg->regs[QPHY_START_CTRL]));
> >   	int ret;
> >   
> > +	qmp->skip_init = qmp->nocsr_reset && phy_initialized;
> > +	/*
> > +	 * We need to check the existence of init sequences in two cases:
> > +	 * 1. The PHY doesn't support no_csr reset.
> > +	 * 2. The PHY supports no_csr reset but isn't initialized by bootloader.
> > +	 * As we can't skip init in these two cases.
> > +	 */
> > +	if (!qmp->skip_init && !cfg->tbls.serdes_num) {
> > +		dev_err(qmp->dev, "no init sequences are available\n");
> "Init sequence not available\n"
>
> > +		return -EINVAL;
> -ENODATA

Will fix in the next version.

> - Mani
--
With best wishes
Wenbin