27.10.2020 22:48, Krzysztof Kozlowski пишет:
On Tue, Oct 27, 2020 at 10:19:28PM +0300, Dmitry Osipenko wrote:
27.10.2020 13:25, Krzysztof Kozlowski пишет:
On Mon, Oct 26, 2020 at 01:16:56AM +0300, Dmitry Osipenko wrote:
External memory controller is interconnected with memory controller and with external memory. Document new interconnect property which turns External Memory Controller into interconnect provider.
Signed-off-by: Dmitry Osipenko digetx@gmail.com
.../bindings/memory-controllers/nvidia,tegra124-emc.yaml | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/Documentation/devicetree/bindings/memory-controllers/nvidia,tegra124-emc.yaml b/Documentation/devicetree/bindings/memory-controllers/nvidia,tegra124-emc.yaml index 278549f9e051..ac00832ceac1 100644 --- a/Documentation/devicetree/bindings/memory-controllers/nvidia,tegra124-emc.yaml +++ b/Documentation/devicetree/bindings/memory-controllers/nvidia,tegra124-emc.yaml @@ -29,6 +29,9 @@ properties: items: - const: emc
- "#interconnect-cells":
- const: 0
- nvidia,memory-controller: $ref: /schemas/types.yaml#/definitions/phandle description:
@@ -327,6 +330,7 @@ required:
- clocks
- clock-names
- nvidia,memory-controller
- "#interconnect-cells"
Another required property, what about all existing users of this binding?
EMC/devfreq drivers check presence of the new properties and ask users to upgrade the DT. The kernel will continue to work fine using older DTBs, but devfreq driver won't load.
If the devfreq was working fine before (with these older DTBs and older kernel) then you break the feature.
If devfreq was not working or was not stable enough, then nothing is broken so such change is accepted.
Which one is then?
Definitely the latter. The current devfreq works okay'ish, but we rely on hardware to recover from temporal FIFO underflows and it's a user-visible problem which this series addresses.