linux-kernel - Re: [PATCH v3 07/18] ARM: dts: qcom: reduce pci IO size to 64K for ipq8064

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Date:   Wed, 13 Apr 2022 15:21:34 +0200
From:   Ansuel Smith <ansuelsmth@...il.com>
To:     Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, Jonathan McDowell <noodles@...th.li>
Subject: Re: [PATCH v3 07/18] ARM: dts: qcom: reduce pci IO size to 64K for
 ipq8064

On Wed, Apr 13, 2022 at 04:19:42PM +0300, Dmitry Baryshkov wrote:
> On 09/03/2022 22:01, Ansuel Smith wrote:
> > The current value for pci IO is problematic for ath10k wifi card
> > commonly connected to ipq8064 SoC.
> > The current value is probably a typo and is actually uncommon to find
> > 1MB IO space even on a x86 arch.
> 
> I checked other Qualcomm platforms (including downstream apq8084.dtsi). All
> of them list 1MB region as IO space.
> 
> Interesting enough I couldn't get PCI to work on my IFC6410 (apq8064). It
> has an ethernet adapter AR8151 sitting on the PCIe bus. The driver probes,
> transmits packets successfully, but receives only garbage. I'm not sure if
> it is the hardware or a software problem. Same adapter works fine on db820c.
>

I didn't understand if device works correctly without this change. 
The alternative to this, is to change the io space globally for every arm
target and it was pointed out that it was a strange change to do. 99%
the 1mb region present on every qcom platform is a copy past error but
still a region that big worked before some kernel version just because
the kernel didn't check them.
So it's both reduce IO in dtsi or extend IO_SPACE_LIMIT for every arm
target.

> > Also with recent changes to the pci
> > driver, pci1 and pci2 now fails to function as any connected device
> > fails any reg read/write. Reduce this to 64K as it should be more than
> > enough and 3 * 64K of total IO space doesn't exceed the IO_SPACE_LIMIT
> > hardcoded for the ARM arch.
> > 
> > Signed-off-by: Ansuel Smith <ansuelsmth@...il.com>
> > Tested-by: Jonathan McDowell <noodles@...th.li>
> > ---
> >   arch/arm/boot/dts/qcom-ipq8064.dtsi | 6 +++---
> >   1 file changed, 3 insertions(+), 3 deletions(-)
> > 
> > diff --git a/arch/arm/boot/dts/qcom-ipq8064.dtsi b/arch/arm/boot/dts/qcom-ipq8064.dtsi
> > index e247bf51df01..36bdfc8db3f0 100644
> > --- a/arch/arm/boot/dts/qcom-ipq8064.dtsi
> > +++ b/arch/arm/boot/dts/qcom-ipq8064.dtsi
> > @@ -918,7 +918,7 @@ pcie0: pci@...00000 {
> >   			#address-cells = <3>;
> >   			#size-cells = <2>;
> > -			ranges = <0x81000000 0 0x0fe00000 0x0fe00000 0 0x00100000   /* downstream I/O */
> > +			ranges = <0x81000000 0 0x0fe00000 0x0fe00000 0 0x00010000   /* downstream I/O */
> >   				  0x82000000 0 0x08000000 0x08000000 0 0x07e00000>; /* non-prefetchable memory */
> >   			interrupts = <GIC_SPI 35 IRQ_TYPE_LEVEL_HIGH>;
> > @@ -969,7 +969,7 @@ pcie1: pci@...00000 {
> >   			#address-cells = <3>;
> >   			#size-cells = <2>;
> > -			ranges = <0x81000000 0 0x31e00000 0x31e00000 0 0x00100000   /* downstream I/O */
> > +			ranges = <0x81000000 0 0x31e00000 0x31e00000 0 0x00010000   /* downstream I/O */
> >   				  0x82000000 0 0x2e000000 0x2e000000 0 0x03e00000>; /* non-prefetchable memory */
> >   			interrupts = <GIC_SPI 57 IRQ_TYPE_LEVEL_HIGH>;
> > @@ -1020,7 +1020,7 @@ pcie2: pci@...00000 {
> >   			#address-cells = <3>;
> >   			#size-cells = <2>;
> > -			ranges = <0x81000000 0 0x35e00000 0x35e00000 0 0x00100000   /* downstream I/O */
> > +			ranges = <0x81000000 0 0x35e00000 0x35e00000 0 0x00010000   /* downstream I/O */
> >   				  0x82000000 0 0x32000000 0x32000000 0 0x03e00000>; /* non-prefetchable memory */
> >   			interrupts = <GIC_SPI 71 IRQ_TYPE_LEVEL_HIGH>;
> 
> 
> -- 
> With best wishes
> Dmitry

-- 
	Ansuel