diff mbox series

[RFC/RFT,v2,09/11] dt-bindings: pci: add lane-map to rockchip PCIe binding

Message ID 20220426132139.26761-10-linux@fw-web.de (mailing list archive)
State New
Headers show
Series RK3568 PCIe V3 support | expand

Commit Message

Frank Wunderlich April 26, 2022, 1:21 p.m. UTC
From: Frank Wunderlich <frank-w@public-files.de>

Create new property for (rockchip) PCIe controller binding to
define lane mapping.

Rockchip driver uses this for bifurcation (true/false) based
on lanes should be splitted across controllers or not.

On rk3568 there are 2 PCIe Controllers which share 2 PCIe lanes.

pcie3x1: pcie@fe270000 //lane1 when using 1+1
pcie3x2: pcie@fe280000 //lane0 when using 1+1

This ends up in one Controller (pcie3x1) uses lane-map = <0 1>; and
the other lane-map = <1 0>; (pcie3x2)

This means there are 2 lanes (count of numbers), one (by position)
is mapped to the first controller, the other one is used on the other
controller.

In rockchip PCIe driver the lane-map is simply converted to the
bifurcation bool instead of direct mapping a specific lane to a
controller.

There is not yet any slot mapping below one controller.
But for binding this may be possible like:

lane-map = <1 2 3 3 4 4 4 4>;
            | | | ...
        lane0 | |
          lane1 |
            lane2

on a 8-lane phy.

This can map lane0 to port1 (number used at this position),
lane1 to port2, lanes 2+3 to port 3 and lanes 4,5,6,7 to port 4.

Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
---
v2:
- new patch
---
 Documentation/devicetree/bindings/pci/rockchip-dw-pcie.yaml | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Comments

Bjorn Helgaas April 26, 2022, 4:04 p.m. UTC | #1
On Tue, Apr 26, 2022 at 03:21:37PM +0200, Frank Wunderlich wrote:
> From: Frank Wunderlich <frank-w@public-files.de>
> 
> Create new property for (rockchip) PCIe controller binding to
> define lane mapping.
> 
> Rockchip driver uses this for bifurcation (true/false) based
> on lanes should be splitted across controllers or not.
> 
> On rk3568 there are 2 PCIe Controllers which share 2 PCIe lanes.
> 
> pcie3x1: pcie@fe270000 //lane1 when using 1+1
> pcie3x2: pcie@fe280000 //lane0 when using 1+1
> 
> This ends up in one Controller (pcie3x1) uses lane-map = <0 1>; and
> the other lane-map = <1 0>; (pcie3x2)
> 
> This means there are 2 lanes (count of numbers), one (by position)
> is mapped to the first controller, the other one is used on the other
> controller.
> 
> In rockchip PCIe driver the lane-map is simply converted to the
> bifurcation bool instead of direct mapping a specific lane to a
> controller.
> 
> There is not yet any slot mapping below one controller.
> But for binding this may be possible like:
> 
> lane-map = <1 2 3 3 4 4 4 4>;
>             | | | ...
>         lane0 | |
>           lane1 |
>             lane2
> 
> on a 8-lane phy.
> 
> This can map lane0 to port1 (number used at this position),
> lane1 to port2, lanes 2+3 to port 3 and lanes 4,5,6,7 to port 4.
> 
> Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
> ---
> v2:
> - new patch
> ---
>  Documentation/devicetree/bindings/pci/rockchip-dw-pcie.yaml | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/pci/rockchip-dw-pcie.yaml b/Documentation/devicetree/bindings/pci/rockchip-dw-pcie.yaml
> index a992970e8b85..998b20b3a9dc 100644
> --- a/Documentation/devicetree/bindings/pci/rockchip-dw-pcie.yaml
> +++ b/Documentation/devicetree/bindings/pci/rockchip-dw-pcie.yaml
> @@ -52,6 +52,8 @@ properties:
>        - const: pclk
>        - const: aux
>  
> +  lane-map: true
> +
>    msi-map: true
>  
>    num-lanes: true
> @@ -74,8 +76,6 @@ properties:
>    reset-names:
>      const: pipe
>  
> -  bifurcation: true
> -

Why are you adding "bifurcation" earlier in the series, then
immediately removing it?  Why not just add "lane-map" directly and
never mention "bifurcation" in the DT at all?

>    vpcie3v3-supply: true
>  
>  required:
> @@ -115,6 +115,7 @@ examples:
>                            "aclk_dbi", "pclk",
>                            "aux";
>              device_type = "pci";
> +            lane-map = <0 1>;
>              linux,pci-domain = <2>;
>              max-link-speed = <2>;
>              msi-map = <0x2000 &its 0x2000 0x1000>;
> -- 
> 2.25.1
> 
> 
> -- 
> linux-phy mailing list
> linux-phy@lists.infradead.org
> https://lists.infradead.org/mailman/listinfo/linux-phy
Frank Wunderlich April 26, 2022, 5:27 p.m. UTC | #2
Hi,

> Gesendet: Dienstag, 26. April 2022 um 18:04 Uhr
> Von: "Bjorn Helgaas" <helgaas@kernel.org>

> > -  bifurcation: true
> > -
>
> Why are you adding "bifurcation" earlier in the series, then
> immediately removing it?  Why not just add "lane-map" directly and
> never mention "bifurcation" in the DT at all?

The original driver used the bifurcation property with vendor prefix which i have dropped.

In v1 there was an Idea to replace this bifurcation setting by something more
generic supporting more that just true/false. So i added lane-map to start
discussion if this is the right way or if i should leave the bifurcation property.

if the lane-map is right, i squash the commits before the commits should land in linux...
this is one cause i tagged the series as RFC.

regards Frank
diff mbox series

Patch

diff --git a/Documentation/devicetree/bindings/pci/rockchip-dw-pcie.yaml b/Documentation/devicetree/bindings/pci/rockchip-dw-pcie.yaml
index a992970e8b85..998b20b3a9dc 100644
--- a/Documentation/devicetree/bindings/pci/rockchip-dw-pcie.yaml
+++ b/Documentation/devicetree/bindings/pci/rockchip-dw-pcie.yaml
@@ -52,6 +52,8 @@  properties:
       - const: pclk
       - const: aux
 
+  lane-map: true
+
   msi-map: true
 
   num-lanes: true
@@ -74,8 +76,6 @@  properties:
   reset-names:
     const: pipe
 
-  bifurcation: true
-
   vpcie3v3-supply: true
 
 required:
@@ -115,6 +115,7 @@  examples:
                           "aclk_dbi", "pclk",
                           "aux";
             device_type = "pci";
+            lane-map = <0 1>;
             linux,pci-domain = <2>;
             max-link-speed = <2>;
             msi-map = <0x2000 &its 0x2000 0x1000>;