From: Shawn Guo <firstname.lastname@example.org>
To: Bjorn Andersson <email@example.com>
Cc: Stephen Boyd <firstname.lastname@example.org>, Rob Herring <email@example.com>,
Loic Poulain <firstname.lastname@example.org>,
Subject: Re: [PATCH 1/3] clk: qcom: smd-rpm: Add rate hooks for clk_smd_rpm_branch_ops
Date: Thu, 16 Sep 2021 13:04:24 +0800 [thread overview]
Message-ID: <20210916050423.GG25255@dragon> (raw)
On Wed, Sep 15, 2021 at 10:23:11AM -0700, Bjorn Andersson wrote:
> On Wed 15 Sep 08:05 PDT 2021, Shawn Guo wrote:
> > On Tue, Sep 14, 2021 at 02:56:28PM -0700, Stephen Boyd wrote:
> > > Quoting Shawn Guo (2021-09-13 19:55:52)
> > > > On QCM2290 platform, the clock xo_board runs at 38400000, while the
> > > > child clock bi_tcxo needs to run at 19200000. That said,
> > > > clk_smd_rpm_branch_ops needs the capability of setting rate. Add rate
> > > > hooks into clk_smd_rpm_branch_ops to make it possible.
> > >
> > > This doesn't sound right. The branch is a simple on/off. If xo_board is
> > > 38.4MHz, then there is an internal divider in the SoC that makes bi_tcxo
> > > (i.e. the root of the entire clk tree) be 19.2MHz. We don't model the
> > > divider, I guess because it isn't very important to. Instead, we tack on
> > > a divider field and implement recalc_rate op. See clk-rpmh.c in the qcom
> > > directory for this.
> > Thanks for the comment, Stephen! To be honest, I copied the
> > implementation from vendor kernel, and wasn't really sure if it's
> > correct or the best.
> > So here is what I get based on your suggestion. Let's me know if
> > it's how you wanted it to be. Thanks!
> > Shawn
> > ----8<---------
> > From 23dda79fee412738f046b89bdd20ef95a24c35cc Mon Sep 17 00:00:00 2001
> > From: Shawn Guo <email@example.com>
> > Date: Wed, 15 Sep 2021 22:00:32 +0800
> > Subject: [PATCH] clk: qcom: smd-rpm: Add a divider field for branch clock
> > Similar to clk-rpmh, clk-smd-rpm has the same need to handle the case
> > where an internal divider is there between xo_board and bi_tcxo. The
> > change is made in the a back compatible way below.
> > - Add div field to struct clk_smd_rpm, and have
> > __DEFINE_CLK_SMD_RPM_BRANCH() assign it.
> > - Update all existing __DEFINE_CLK_SMD_RPM_BRANCH() wrappers to pass a
> > zero div.
> > - Add DEFINE_CLK_SMD_RPM_BRANCH_DIV() which doesn't take rate argument
> > but div.
> > - Update clk_smd_rpm_recalc_rate() to handle div and add it as
> > .recalc_rate of clk_smd_rpm_branch_ops.
> This looks good to me.
> And the confirmed that the xo_board in sdm630.dtsi (and hence SDM660) is
> wrong, it should be 38.4MHz as well.
Hmm, I see CAF kernel has 19.2MHz for SDM630/660 xo_board clock. Or am
I looking at the wrong place?
> Unfortunately adding the appropriate divider to the sdm660 bcxo would
> break existing .dtsi (but we can probably convince the community that it
> would be ok, if we do it now).
next prev parent reply other threads:[~2021-09-16 5:04 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-14 2:55 [PATCH 0/3] Add QCM2290 RPM clocks support Shawn Guo
2021-09-14 2:55 ` [PATCH 1/3] clk: qcom: smd-rpm: Add rate hooks for clk_smd_rpm_branch_ops Shawn Guo
2021-09-14 21:56 ` Stephen Boyd
2021-09-15 15:05 ` Shawn Guo
2021-09-15 17:23 ` Bjorn Andersson
2021-09-15 17:44 ` Bjorn Andersson
2021-09-16 5:04 ` Shawn Guo [this message]
2021-09-15 2:55 ` Bjorn Andersson
2021-09-15 15:12 ` Shawn Guo
2021-09-14 2:55 ` [PATCH 2/3] dt-bindings: clk: qcom,rpmcc: Document QCM2290 compatible Shawn Guo
2021-09-14 2:55 ` [PATCH 3/3] clk: qcom: smd-rpm: Add QCM2290 RPM clock support Shawn Guo
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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.