-----Original Message-----
From: Ulf Hansson [mailto:ulf.hansson@linaro.org]
Sent: 2021年8月16日 21:43
To: Bough Chen <haibo.chen@nxp.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>; Shawn Guo
[off-list ref]; Rob Herring [off-list ref]; Sascha Hauer
[off-list ref]; Sascha Hauer [off-list ref]; Fabio
Estevam [off-list ref]; linux-mmc [off-list ref];
dl-linux-imx [off-list ref]; DTML [off-list ref]; Linux
ARM [off-list ref]
Subject: Re: [PATCH 3/6] dt-bindings: mmc: fsl-imx-esdhc: add
fsl,sdio-async-interrupt-enabled binding

On Mon, 16 Aug 2021 at 15:00, [off-list ref] wrote:

quoted

From: Haibo Chen <haibo.chen@nxp.com>

Add a new fsl,sdio-async-interrupt-enabled binding for sdio devices
which enable the async interrupt function. When get this property,
driver will avoid to use DAT[1] for hardware auto tuning check.

Signed-off-by: Haibo Chen <haibo.chen@nxp.com>
---
 .../devicetree/bindings/mmc/fsl-imx-esdhc.yaml         | 10

++++++++++

quoted

 1 file changed, 10 insertions(+)

diff --git a/Documentation/devicetree/bindings/mmc/fsl-imx-esdhc.yaml

b/Documentation/devicetree/bindings/mmc/fsl-imx-esdhc.yaml
index b5baf439fbac..8a9f1775b0e2 100644

--- a/Documentation/devicetree/bindings/mmc/fsl-imx-esdhc.yaml
+++ b/Documentation/devicetree/bindings/mmc/fsl-imx-esdhc.yaml

@@ -122,6 +122,16 @@ properties:
       - const: state_200mhz
       - const: sleep

+  fsl,sdio-async-interrupt-enabled:
+    description: |
+      Recommend for SDIO cards that enables SDIO async interrupt for

SDR104 and SDR50

quoted

+      operating modes. SDIO async interrupt uses DAT[1] to signal the

card's interrupt.

quoted

+      uSDHC tuning mechanism must use DAT[0] and CMD signals to avoid

a possible

quoted

+      conflict and incorrect delay line calculated by the uSDHC auto tuning

mechanism.

quoted

+      Enabling this device tree property is only recommended for layouts

that are

quoted

+      matching the SD interface length.
+    type: boolean

We already have a common mmc property, "cap-sdio-irq", that tells whether
the controller supports SDIO irqs (which is delivered on DAT1).

Can't you use this instead?

Hi Ulf,

Thanks for your quick reply!

According to our WiFi team reply, the sdio-irq has two types. Sync interrupt and Async interrupt.
When WiFi send out the interrupt signal during the interrupt period, if it sync with clock pad(just as
when send out data), then this is sync interrupt. When this interrupt not sync with clock, it is async
interrupt. Async interrupt has a better overall performance than sync interrupt.

Logically, auto tuning circuit should only take care of the data and cmd line, and ignore interrupt signal.
But unfortunately current i.mx-usdhc IP do not ignore interrupt signal. So it detect the interrupt signal,
and take this signal as a data signal, and adjust the delay cell accordingly. For sync interrupt, due to it
sync with clock, so no affect, but for async interrupt, it will involve wrong delay cell change randomly.

I involve a new property here, because in sdhci.c, we default use this "cap-sdio-irq" for all sdio/sd/mmc.
I need one property which can use only for sdio device, and only when sdio device enable async-interrupt.

Best Regards
Haibo Chen

quoted

+
 required:
   - compatible
   - reg
--
2.17.1

Kind regards
Uffe