archive mirror
 help / color / mirror / Atom feed
From: Stephen Boyd <>
To: Stephan Gerhold <>
Cc: Andy Gross <>,
	Bjorn Andersson <>,
	Elliot Berman <>,,,
	Brian Masney <>,
	Jeffrey Hugo <>,
	Douglas Anderson <>
Subject: Re: [PATCH v2] firmware: qcom_scm: Only compile legacy calls on ARM
Date: Wed, 07 Apr 2021 17:12:06 -0700	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

Quoting Stephan Gerhold (2021-04-05 05:50:26)
> On Fri, Apr 02, 2021 at 10:21:58AM -0700, Stephen Boyd wrote:
> > 
> > Ah right, the whole secure world running in 32-bit mode thing. Is
> > msm8916 the only SoC that's using that? Or are there more? If only
> > msm8916 is affected then we could use a combination of CONFIG_ARM64 and
> > the compatible string to differentiate and then if more SoCs use 32-bit
> > secure world then we could have a new compatible string like qcom,scm-32
> > that tells us this fact. Maybe this was all discussed before and I
> > missed it. Either way, I'm trying to get rid of this boot call so that
> > we don't have to bounce to the firmware an extra time to figure out
> > something we can figure out from the kernel arch and scm compatible
> > string.
> At least MSM8994 also uses SMC32 from what I heard. Overall it's
> probably quite hard to get that right now since all boards were tested
> with the dynamic detection so far. I suppose you could do the opposite,
> add an optional qcom,scm-64 to skip the detection step and force SMC64.

Isn't SMC64 going to be the overall majority going forward? Legacy
convention is for sure limited to CONFIG_ARM so I'll send another
follow-up patch to add a warning if we find legacy on CONFIG_ARM64.
SMC32 is hopefully no longer being produced given that it was introduced
at the time that the bootloader team wasn't supporting PSCI and didn't
want to support it. So we're making all new boards/SoCs/firmwares do
this calling convention probing to figure out something they already

Maybe we should probe the calling convention on msm8994/msm8916 and
otherwise assume SMC64 on CONFIG_ARM64 kernels. I'd expect the exception
list to be smaller that way.

> Also note that this could even be firmware-specific, not necessarily
> SoC-specific. There are some ancient MSM8916 firmwares that have legacy
> instead of SMC32. I could also imagine that there is also some SoC where
> there are different firmware versions with SMC32 or SMC64.

Sure but in theory the firmware would update the DT to indicate what
sort of firmware is there.

> Plus, IMO the overhead for this detection is negligible. At least it
> ensures that we always use the right calling convention. The PSCI code
> probably does much more firmware calls to figure out all supported
> features.

Heh, it tried to ensure we use the right calling convention but broke
things in the process, because the way of detecting the convention isn't
always there. I wouldn't be surprised if this comes up again for other
boards that use TF-A.

  reply	other threads:[~2021-04-08  0:12 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-23 22:43 [PATCH v2] firmware: qcom_scm: Only compile legacy calls on ARM Stephen Boyd
2021-04-01  1:26 ` Stephen Boyd
2021-04-01  1:52 ` Bjorn Andersson
2021-04-02  1:12 ` Elliot Berman
2021-04-02  6:58   ` Stephen Boyd
2021-04-02 10:18     ` Stephan Gerhold
2021-04-02 17:21       ` Stephen Boyd
2021-04-05 12:50         ` Stephan Gerhold
2021-04-08  0:12           ` Stephen Boyd [this message]
2021-04-08  7:19             ` Stephan Gerhold
2021-04-08 21:18               ` Stephen Boyd

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \ \ \ \ \ \ \ \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).