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Message-ID: <20250124080126.itc6qoutn65isnej@thinkpad>
Date: Fri, 24 Jan 2025 13:31:26 +0530
From: Manivannan Sadhasivam <mani@...nel.org>
To: Hongxing Zhu <hongxing.zhu@....com>
Cc: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
"l.stach@...gutronix.de" <l.stach@...gutronix.de>,
"bhelgaas@...gle.com" <bhelgaas@...gle.com>,
"lpieralisi@...nel.org" <lpieralisi@...nel.org>,
"kw@...ux.com" <kw@...ux.com>, "robh@...nel.org" <robh@...nel.org>,
"krzk+dt@...nel.org" <krzk+dt@...nel.org>,
"conor+dt@...nel.org" <conor+dt@...nel.org>,
"shawnguo@...nel.org" <shawnguo@...nel.org>,
Frank Li <frank.li@....com>,
"s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
"festevam@...il.com" <festevam@...il.com>,
"imx@...ts.linux.dev" <imx@...ts.linux.dev>,
"kernel@...gutronix.de" <kernel@...gutronix.de>,
"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
"linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v7 02/10] PCI: imx6: Add ref clock for i.MX95 PCIe
On Mon, Jan 20, 2025 at 02:49:09AM +0000, Hongxing Zhu wrote:
> > -----Original Message-----
> > From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> > Sent: 2025年1月19日 15:03
> > To: Hongxing Zhu <hongxing.zhu@....com>
> > Cc: l.stach@...gutronix.de; bhelgaas@...gle.com; lpieralisi@...nel.org;
> > kw@...ux.com; robh@...nel.org; krzk+dt@...nel.org; conor+dt@...nel.org;
> > shawnguo@...nel.org; Frank Li <frank.li@....com>; s.hauer@...gutronix.de;
> > festevam@...il.com; imx@...ts.linux.dev; kernel@...gutronix.de;
> > linux-pci@...r.kernel.org; linux-arm-kernel@...ts.infradead.org;
> > devicetree@...r.kernel.org; linux-kernel@...r.kernel.org
> > Subject: Re: [PATCH v7 02/10] PCI: imx6: Add ref clock for i.MX95 PCIe
> >
> > On Tue, Nov 26, 2024 at 03:56:54PM +0800, Richard Zhu wrote:
> > > Add "ref" clock to enable reference clock. To avoid breaking DT
> > > backwards compatibility, i.MX95 REF clock might be optional. Use
> > > devm_clk_get_optional() to fetch i.MX95 PCIe optional clocks in driver.
> > >
> > > If use external clock, ref clock should point to external reference.
> > >
> > > If use internal clock, CREF_EN in LAST_TO_REG controls reference
> > > output, which implement in drivers/clk/imx/clk-imx95-blk-ctl.c.
> > >
> > > Signed-off-by: Richard Zhu <hongxing.zhu@....com>
> > > Reviewed-by: Frank Li <Frank.Li@....com>
> > > ---
> > > drivers/pci/controller/dwc/pci-imx6.c | 16 +++++++++++-----
> > > 1 file changed, 11 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/drivers/pci/controller/dwc/pci-imx6.c
> > > b/drivers/pci/controller/dwc/pci-imx6.c
> > > index 385f6323e3ca..f7e928e0a018 100644
> > > --- a/drivers/pci/controller/dwc/pci-imx6.c
> > > +++ b/drivers/pci/controller/dwc/pci-imx6.c
> > > @@ -103,6 +103,7 @@ struct imx_pcie_drvdata {
> > > const char *gpr;
> > > const char * const *clk_names;
> > > const u32 clks_cnt;
> > > + const u32 clks_optional_cnt;
> > > const u32 ltssm_off;
> > > const u32 ltssm_mask;
> > > const u32 mode_off[IMX_PCIE_MAX_INSTANCES]; @@ -1306,9 +1307,8
> > @@
> > > static int imx_pcie_probe(struct platform_device *pdev)
> > > struct device_node *np;
> > > struct resource *dbi_base;
> > > struct device_node *node = dev->of_node;
> > > - int ret;
> > > + int i, ret, req_cnt;
> > > u16 val;
> > > - int i;
> > >
> > > imx_pcie = devm_kzalloc(dev, sizeof(*imx_pcie), GFP_KERNEL);
> > > if (!imx_pcie)
> > > @@ -1358,9 +1358,13 @@ static int imx_pcie_probe(struct platform_device
> > *pdev)
> > > imx_pcie->clks[i].id = imx_pcie->drvdata->clk_names[i];
> > >
> > > /* Fetch clocks */
> > > - ret = devm_clk_bulk_get(dev, imx_pcie->drvdata->clks_cnt, imx_pcie->clks);
> > > + req_cnt = imx_pcie->drvdata->clks_cnt -
> > imx_pcie->drvdata->clks_optional_cnt;
> > > + ret = devm_clk_bulk_get(dev, req_cnt, imx_pcie->clks);
> > > if (ret)
> > > return ret;
> > > + imx_pcie->clks[req_cnt].clk = devm_clk_get_optional(dev, "ref");
> > > + if (IS_ERR(imx_pcie->clks[req_cnt].clk))
> > > + return PTR_ERR(imx_pcie->clks[req_cnt].clk);
> >
> > I think you should just switch to devm_clk_bulk_get_all() instead of getting the
> > clks separately. As I told previously, the DT binding should ensure that correct
> > clocks for the platforms are defined in DT and the driver has no business in
> > validating it. Driver should trust the DT instead (unless there is a valid reason to not
> > do so).
> >
> > >
> > > if (imx_check_flag(imx_pcie, IMX_PCIE_FLAG_HAS_PHYDRV)) {
> > > imx_pcie->phy = devm_phy_get(dev, "pcie-phy"); @@ -1509,6 +1513,7
> > > @@ static const char * const imx8mm_clks[] = {"pcie_bus", "pcie",
> > > "pcie_aux"}; static const char * const imx8mq_clks[] = {"pcie_bus",
> > > "pcie", "pcie_phy", "pcie_aux"}; static const char * const
> > > imx6sx_clks[] = {"pcie_bus", "pcie", "pcie_phy", "pcie_inbound_axi"};
> > > static const char * const imx8q_clks[] = {"mstr", "slv", "dbi"};
> > > +static const char * const imx95_clks[] = {"pcie_bus", "pcie",
> > > +"pcie_phy", "pcie_aux", "ref"};
> >
> > And these static clock defines will go away too.
> >
> Hi Mani:
> Thanks for your comments.
> The suggestions are very nice. How about kick off further optimization later?
Sure. This series got merged already.
> Since the changes would impact all i.MX PCIes.
> Meanwhile, I'm a little worry about that there is no consensus yet on relying
> entirely on the dt binding check.
Consensus between whom?
- Mani
--
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