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Date: Sun, 3 Jul 2022 16:58:09 -0700
From: Brad Larson <brad@...sando.io>
To: Serge Semin <fancer.lancer@...il.com>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
Linux ARM <linux-arm-kernel@...ts.infradead.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
linux-mmc <linux-mmc@...r.kernel.org>,
Adrian Hunter <adrian.hunter@...el.com>,
Al Cooper <alcooperx@...il.com>,
Andy Shevchenko <andy.shevchenko@...il.com>,
Arnd Bergmann <arnd@...db.de>, blarson@....com,
Catalin Marinas <catalin.marinas@....com>,
Gabriel Somlo <gsomlo@...il.com>, gerg@...ux-m68k.org,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Lee Jones <lee.jones@...aro.org>,
Mark Brown <broonie@...nel.org>,
Masahiro Yamada <yamada.masahiro@...ionext.com>,
Philipp Zabel <p.zabel@...gutronix.de>,
Pratyush Yadav <p.yadav@...com>,
Randy Dunlap <rdunlap@...radead.org>,
Rob Herring <robh+dt@...nel.org>, samuel@...lland.org,
suravee.suthikulpanit@....com,
Tom Lendacky <thomas.lendacky@....com>,
Ulf Hansson <ulf.hansson@...aro.org>,
Will Deacon <will@...nel.org>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@...r.kernel.org>
Subject: Re: [PATCH v5 04/15] dt-bindings: spi: dw: Add AMD Pensando Elba SoC
SPI Controller bindings
Hi Sergey,
On Tue, Jun 21, 2022 at 3:12 AM Serge Semin <fancer.lancer@...il.com> wrote:
>
> On Tue, Jun 21, 2022 at 09:00:36AM +0200, Krzysztof Kozlowski wrote:
> > On 20/06/2022 22:04, Serge Semin wrote:
> > > On Mon, Jun 20, 2022 at 09:46:25PM +0200, Krzysztof Kozlowski wrote:
> > >> On 20/06/2022 21:30, Serge Semin wrote:
> > >>> On Mon, Jun 13, 2022 at 12:56:47PM -0700, Brad Larson wrote:
> > >>>> From: Brad Larson <blarson@....com>
> > >>>>
> > >>>> The AMD Pensando Elba SoC has integrated the DW APB SPI Controller
> > >>>>
> > >>>> Signed-off-by: Brad Larson <blarson@....com>
> > >>>> ---
> > >>>> Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.yaml | 2 ++
> > >>>> 1 file changed, 2 insertions(+)
> > >>>>
> > >>>> diff --git a/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.yaml b/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.yaml
> > >>>> index e25d44c218f2..2a55b947cffc 100644
> > >>>> --- a/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.yaml
> > >>>> +++ b/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.yaml
> > >>>> @@ -73,6 +73,8 @@ properties:
> > >>>> - renesas,r9a06g032-spi # RZ/N1D
> > >>>> - renesas,r9a06g033-spi # RZ/N1S
> > >>>> - const: renesas,rzn1-spi # RZ/N1
> > >>>
> > >>>> + - description: AMD Pensando Elba SoC SPI Controller
> > >>>> + const: amd,pensando-elba-spi
> > >>>
> > >>> Not enough. The driver requires to have a phandle reference to the
> > >>> Pensando System Controller. So the property like
> > >>> "amd,pensando-elba-syscon" is also needed to be added to the DT schema
> > >>> otherwise should the dt-schema tool correctly handle the
> > >>> "unevaluatedProperties: false" setting (Rob says it isn't fully
> > >>> supported at the moment), the dtbs_check procedure will fail on your
> > >>> dts evaluation.
> > >>
> > >
> > >> The property was here before, now removed, so I assume it was also
> > >> removed from the driver and DTS. Isn't that the case?
> > >
> > > Ah, the property has been indeed removed. The driver now searches for
> > > the system controller by the next compatible string:
> > > "amd,pensando-elba-syscon" using the
> > > syscon_regmap_lookup_by_compatible() method. My mistake. Sorry for the
> > > noise.
> > >
>
> > > * Though personally I'd prefer to have a property with the phandle
> > > reference in order to signify the connection between the system controller
> > > and the SPI-controller. Otherwise the implicit DT bindings like having
> > > the "amd,pensando-elba-syscon"-compatible syscon gets to be
> > > hidden behind the DT scene. But seeing we have already got the Microsemi
> > > platform with such semantic, I can't insist on fixing this.
> >
> > I agree entirely, this should be explicit syscon-type property. Looking
> > up for compatibles:
> > - creates hidden (not expressed via bindings) dependency between nodes,
> > - is not portable and several people struggled with it later and needed
> > backward-compatible code (many examples, let's just give recent one: [1])
> >
> >
> > [1]
> > https://lore.kernel.org/all/20220619151225.209029-10-tmaimon77@gmail.com/
>
> Seems even more reasonable now. Thanks for providing a bright example
> justifying the property-based approach.
>
> @Brad, could you get back the property with a phandle to the syscon
> DT-node? (No need in adding the CS CSR address as the phandle argument,
> just a phandle.)
Replying to the sequence of review inputs. The below change to
version 5 brings back the phandle without the earlier argument that
complicated the binding (was the motivation for moving in this
direction in earlier version). Passes dtbs_check.
--- a/drivers/spi/spi-dw-mmio.c
+++ b/drivers/spi/spi-dw-mmio.c
@@ -285,12 +285,17 @@ static void dw_spi_elba_set_cs(struct spi_device
*spi, bool enable)
static int dw_spi_elba_init(struct platform_device *pdev,
struct dw_spi_mmio *dwsmmio)
{
+ struct device_node *np = pdev->dev.of_node;
+ struct device_node *node;
struct dw_spi_elba *dwselba;
struct regmap *regmap;
- regmap = syscon_regmap_lookup_by_compatible("amd,pensando-elba-syscon");
- if (IS_ERR(regmap))
- return PTR_ERR(regmap);
+ node = of_parse_phandle(np, "pensando,elba-syscon-spics", 0);
+ if (node) {
+ regmap = syscon_node_to_regmap(node);
+ if (IS_ERR(regmap))
+ return PTR_ERR(regmap);
+ }
diff --git a/arch/arm64/boot/dts/amd/elba.dtsi
b/arch/arm64/boot/dts/amd/elba.dtsi
index 9739641261c3..ec48be4cfe48 100644
--- a/arch/arm64/boot/dts/amd/elba.dtsi
+++ b/arch/arm64/boot/dts/amd/elba.dtsi
@@ -98,6 +98,7 @@
reg = <0x0 0x2800 0x0 0x100>;
#address-cells = <1>;
#size-cells = <0>;
+ pensando,elba-syscon-spics = <&syscon>;
clocks = <&ahb_clk>;
interrupts = <GIC_SPI 9 IRQ_TYPE_LEVEL_HIGH>;
num-cs = <2>;
--- a/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.yaml
+++ b/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.yaml
@@ -37,6 +37,15 @@ allOf:
else:
required:
- interrupts
+ - if:
+ properties:
+ compatible:
+ contains:
+ enum:
+ - amd,pensando-elba-spi
+ then:
+ required:
+ - pensando,elba-syscon-spics
properties:
compatible:
Regards,
Brad
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