[PATCH v3 1/2] dt-bindings: mmc: Document no-mmc-poweroff-suspend property

[Kamal Dasu]

On some platforms, firmware accesses the (e)MMC card directly during
system resume from Suspend-to-DRAM, before the kernel's own resume
path has run, in order to load boot code using hard wired logic that
is not field updatable. This requires the card to remain powered
and responsive throughout suspend: it cannot be put to sleep, sent a
power-off notification, or have its supply removed.

Add a no-mmc-poweroff-suspend flag property so affected boards can
tell the mmc core to keep the card powered across suspend instead of
sleeping or powering it off.

Signed-off-by: Kamal Dasu <kamal.dasu@xxxxxxxxxxxx>
---
Changes in v3:
  - Renamed from no-mmc-sleep; dropped S_A_TIMEOUT framing per Ulf.

Changes in v2:
  - New patch, replacing v1's card-level quirk, per Ulf.

 .../devicetree/bindings/mmc/mmc-controller-common.yaml | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/Documentation/devicetree/bindings/mmc/mmc-controller-common.yaml b/Documentation/devicetree/bindings/mmc/mmc-controller-common.yaml
index 3d7195e9461c..5f7b3f8ef1dd 100644
--- a/Documentation/devicetree/bindings/mmc/mmc-controller-common.yaml
+++ b/Documentation/devicetree/bindings/mmc/mmc-controller-common.yaml
@@ -232,6 +232,16 @@ properties:
     description:
       All eMMC HS400 modes are not supported.
 
+  no-mmc-poweroff-suspend:
+    $ref: /schemas/types.yaml#/definitions/flag
+    description:
+      On this platform, firmware accesses the attached (e)MMC card
+      directly during system resume, before the kernel's own resume
+      path runs. The card must therefore stay powered throughout
+      suspend, and the controller must not send it a sleep or
+      power-off notification. The kernel re-initializes the card
+      after resume, since firmware may have already reset it.
+
   dsr:
     description:
       Value the card Driver Stage Register (DSR) should be programmed
-- 
2.34.1