Re: [PATCH net-next v2 2/2] dt: bindings: add new dt entries for brcmfmac

Hi Arend,
I appreciate your response. In my opinion, it has nothing to do with
SDIO host, because it defines "quirks" in the driver itself.
If I get it right, you mean something like this:

mmc3: mmc@1c12000 {
...
        broken-sg-support;
        sd-head-align = 4;
        sd-sgentry-align = 512;

        brcmf: wifi@1 {
                ...
        };
};

Where dt: bindings documentation for these entries should reside?
In generic MMC bindings? Well, this is the very special case and
mmc-linux maintainer will unlikely to accept these changes.
Also, extra kernel code modification might be required. It could make
quite trivial change much more complex.

Also I am not sure if the broken-sg-support is still needed. We added that for omap_hsmmc, but that has since changed to scatter-gather emulation so it might not be needed anymore.

I've experienced the problem with rk3288 (dw-mmc host) and sdio
settings like above solved it.
Frankly, I haven't investigated any deeper which one of the settings
helped in my case yet...
I will try to get rid of broken-sg-support first and let you know if
it does make any difference.

All the best,
  Alex.

On 19 March 2018 at 16:31, Arend van Spriel
[off-list ref] wrote:

On 3/19/2018 2:40 AM, Alexey Roslyakov wrote:

quoted

In case if the host has higher align requirements for SG items, allow
setting device-specific aligns for scatterlist items.

Signed-off-by: Alexey Roslyakov <redacted>
---
  Documentation/devicetree/bindings/net/wireless/brcm,bcm43xx-fmac.txt | 5
+++++
  1 file changed, 5 insertions(+)

diff --git
a/Documentation/devicetree/bindings/net/wireless/brcm,bcm43xx-fmac.txt
b/Documentation/devicetree/bindings/net/wireless/brcm,bcm43xx-fmac.txt
index 86602f264dce..187b8c1b52a7 100644

--- a/Documentation/devicetree/bindings/net/wireless/brcm,bcm43xx-fmac.txt
+++ b/Documentation/devicetree/bindings/net/wireless/brcm,bcm43xx-fmac.txt

@@ -17,6 +17,11 @@ Optional properties:
        When not specified the device will use in-band SDIO interrupts.
   - interrupt-names : name of the out-of-band interrupt, which must be

set
        to "host-wake".
+ - brcm,broken-sg-support : boolean flag to indicate that the SDIO host
+       controller has higher align requirement than 32 bytes for each
+       scatterlist item.
+ - brcm,sd-head-align : alignment requirement for start of data buffer.
+ - brcm,sd-sgentry-align : length alignment requirement for each sg
entry.

Hi Alexey,

Thanks for the patch. However, the problem with these is that they are
characterizing the host controller and not the wireless device. So from
device tree perspective , which is to describe the hardware, these
properties should be SDIO host controller properties. Also I am not sure if
the broken-sg-support is still needed. We added that for omap_hsmmc, but
that has since changed to scatter-gather emulation so it might not be needed
anymore.

Regards,
Arend

-- 
With best regards,
  Alexey Roslyakov
Email: alexey.roslyakov@gmail.com