linux-kernel - Re: [PATCH v4 8/8] PCI: dwc: Introduce region limit from DT

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Date:   Tue, 14 Mar 2023 23:48:38 +0300
From:   Serge Semin <Sergey.Semin@...kalelectronics.ru>
To:     Bjorn Helgaas <helgaas@...nel.org>
CC:     Elad Nachman <enachman@...vell.com>,
        <thomas.petazzoni@...tlin.com>, <bhelgaas@...gle.com>,
        <lpieralisi@...nel.org>, <robh@...nel.org>, <kw@...ux.com>,
        <krzysztof.kozlowski+dt@...aro.org>, <linux-pci@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 8/8] PCI: dwc: Introduce region limit from DT

Hi Bjorn

On Mon, Mar 13, 2023 at 02:48:02PM -0500, Bjorn Helgaas wrote:
> [+cc Serge, who has done most of the recent work in this file]
> 

Thanks for sending copy to me. I'll have a look at the series on
this week.

-Serge(y)

> On Mon, Mar 13, 2023 at 02:40:16PM +0200, Elad Nachman wrote:
> > From: Elad Nachman <enachman@...vell.com>
> > 
> > Allow dts override of region limit for SOCs with older Synopsis
> > Designware PCIe IP but with greater than 32-bit address range support,
> > such as the Armada 7020/7040/8040 family of SOCs by Marvell,
> > when the DT file places the PCIe window above the 4GB region.
> > The Synopsis Designware PCIe IP in these SOCs is too old to specify the
> > highest memory location supported by the PCIe, but practically supports
> > such locations. Allow these locations to be specified in the DT file.
> > DT property is called num-regionmask , and can range between 33 and 64.
> 
> s/Synopsis/Synopsys/ (several occurrences)
> 
> s/Designware/DesignWare/ (several occurrences)
> 
> Remove space before comma.
> 
> > Signed-off-by: Elad Nachman <enachman@...vell.com>
> > ---
> > v4:
> >    1) Fix blank lines removal / addition
> > 
> >    2) Remove usage of variable with same name as dt binding property
> > 
> >  drivers/pci/controller/dwc/pcie-designware.c | 12 ++++++++++--
> >  1 file changed, 10 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
> > index 53a16b8b6ac2..9773c110c733 100644
> > --- a/drivers/pci/controller/dwc/pcie-designware.c
> > +++ b/drivers/pci/controller/dwc/pcie-designware.c
> > @@ -735,8 +735,10 @@ static void dw_pcie_link_set_max_speed(struct dw_pcie *pci, u32 link_gen)
> >  void dw_pcie_iatu_detect(struct dw_pcie *pci)
> >  {
> >  	int max_region, ob, ib;
> > -	u32 val, min, dir;
> > +	u32 val, min, dir, ret;
> >  	u64 max;
> > +	struct device *dev = pci->dev;
> > +	struct device_node *np = dev->of_node;
> >  
> >  	val = dw_pcie_readl_dbi(pci, PCIE_ATU_VIEWPORT);
> >  	if (val == 0xFFFFFFFF) {
> > @@ -781,7 +783,13 @@ void dw_pcie_iatu_detect(struct dw_pcie *pci)
> >  		dw_pcie_writel_atu(pci, dir, 0, PCIE_ATU_UPPER_LIMIT, 0xFFFFFFFF);
> >  		max = dw_pcie_readl_atu(pci, dir, 0, PCIE_ATU_UPPER_LIMIT);
> >  	} else {
> > -		max = 0;
> > +		/* Allow dts override of region limit for older IP with above 32-bit support: */
> 
> Reflow comment to fit in 80 columns.
> 
> > +		ret = of_property_read_u32(np, "num-regionmask", &val);
> > +		if (!ret && val > 32) {
> > +			max = GENMASK(val - 33, 0);
> > +			dev_info(pci->dev, "Overriding region limit to %u bits\n", val);
> > +		} else
> > +			max = 0;
> >  	}
> >  
> >  	pci->num_ob_windows = ob;
> > -- 
> > 2.17.1
> > 
>