Re: [PATCH V1] dt-bindings: mmc: sdhci-msm: Add CQE reg map

Hi,

On Wed, Feb 12, 2020 at 4:00 AM Veerabhadrarao Badiganti
[off-list ref] wrote:

On 2/11/2020 10:12 PM, Doug Anderson wrote:

quoted

Hi,

On Tue, Feb 11, 2020 at 7:29 AM Veerabhadrarao Badiganti
[off-list ref] wrote:

quoted

CQE feature has been enabled on sdhci-msm. Add CQE reg map
that needs to be supplied for supporting CQE feature.

Change-Id: I788c4bd5b7cbca16bc1030a410cc5550ed7204e1
Signed-off-by: Veerabhadrarao Badiganti <redacted>
---
  Documentation/devicetree/bindings/mmc/sdhci-msm.txt | 5 +++++
  1 file changed, 5 insertions(+)

diff --git a/Documentation/devicetree/bindings/mmc/sdhci-msm.txt b/Documentation/devicetree/bindings/mmc/sdhci-msm.txt
index 7ee639b..eaa0998 100644
--- a/Documentation/devicetree/bindings/mmc/sdhci-msm.txt
+++ b/Documentation/devicetree/bindings/mmc/sdhci-msm.txt

@@ -27,6 +27,11 @@ Required properties:
  - reg: Base address and length of the register in the following order:
         - Host controller register map (required)
         - SD Core register map (required for msm-v4 and below)
+       - CQE register map (Optional, needed only for eMMC and msm-v4.2 above)

I did a quick search and it appears that SD cards implementing 6.0 of
the spec can also use CQE.  Is that correct?  If so, maybe remove the
part about "eMMC"?

On qcom platforms, only SDHC instance meant for eMMC has the CQE support.
So mentioned that its needed only for eMMC.

Ah, got it.  Maybe mention this in the bindings?  Like "Optional, CQE
is only implemented on controllers meant for eMMC and version v4.2 and
above"

quoted

Maybe also change "needed" to "useful" to make it clear that this
entry isn't actually required for all msm-v4.2 controllers?

sure.

quoted

quoted

+- reg-names: When CQE register map is supplied, below reg-names are required
+       - "hc_mem" for Host controller register map
+       - "core_mem" for SD cpre regoster map

s/regoster/register

Oh, also s/cpre/core

quoted

quoted

+       - "cqhci_mem" for CQE register map

I'm at least slightly confused.  You say that reg-names are there only
if CQE register map is supplied.  ...and that requires 4.2 and above.
...but "core_mem" is only there on 4.0 and below.  So there should
never be a "core_mem" entry?

core_mem is present till <v5.0
cqhci_mem is present on >=v4.2
Say, for version v4.2 both are present; .... and for v5.0 only cqhci_mem
is present.

Both hc reg-map and core reg-map are being accessed through index.
So no need to list the reg names 'hc_mem' & 'core_mem' in general.

But coming to cqhci reg-map we can't access it with fixed index, since
its index varies between 1/2
based on controller version.

So we are accessing it through reg-names. Since reg-names has to be
associated with corresponding
reg maps, other two reg-names (hc_mem & core_mem) also need to br listed
when cqhci_mem is listed.

That is the reason, I mentioned it like these are needed only cqe reg
map is supplied.
If it is creating confusion, i will remove that statement.

Ah.  I think I got confused!  When I saw "msm-v4 and below" in the
description of "SD Core register map", I assumed that means that
"v4.2" didn't have it.  Maybe would be less confusing to change to:

- SD Core register map (required for controllers earlier than msm-v5)

Then I think what you have can be fine.

quoted

Trying to specify that sanely in free-form text seems like it's gonna
be hard and not worth it.  You should probably transition to yaml
first?


I will also note that Rob isn't a huge fan of "reg-names".  In a
different conversation I think you mentioned you had a reason for
having it.  I guess just be prepared to defend yourself against Rob if
you feel strongly about keeping reg-names.

Sure. Its the same reason mentioned in above comment.

OK.  You've convinced me.  It's still up to Rob but it seems like you
have a good justification now that I understand it better..  ;-)

I think you could send out a v2 with the small wording changes and
maybe it would be landable, but you'd want to follow up rather soon
with the yaml conversion.


-Doug