From: Cristian Ciocaltea <cristian.ciocaltea@gmail.com>
To: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Cc: "Stephen Boyd" <sboyd@kernel.org>,
"Rob Herring" <robh+dt@kernel.org>,
"Andreas Färber" <afaerber@suse.de>,
"Michael Turquette" <mturquette@baylibre.com>,
"Edgar Bernardi Righi" <edgar.righi@lsitec.org.br>,
linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-actions@lists.infradead.org, linux-kernel@vger.kernel.org,
devicetree@vger.kernel.org
Subject: Re: [PATCH 3/6] clk: actions: Fix bisp_factor_table based clocks on Owl S500 SoC
Date: Thu, 27 May 2021 16:34:52 +0300 [thread overview]
Message-ID: <20210527133452.GB1300160@BV030612LT> (raw)
In-Reply-To: <20210526101830.GE10723@work>
On Wed, May 26, 2021 at 03:48:30PM +0530, Manivannan Sadhasivam wrote:
> On Tue, Mar 16, 2021 at 08:37:53PM +0200, Cristian Ciocaltea wrote:
> > On Tue, Mar 16, 2021 at 09:47:39AM +0530, Manivannan Sadhasivam wrote:
> > > On Mon, Mar 08, 2021 at 07:18:28PM +0200, Cristian Ciocaltea wrote:
> > > > The following clocks of the Actions Semi Owl S500 SoC have been defined
> > > > to use a shared clock factor table 'bisp_factor_table[]': DE[1-2], VCE,
> > > > VDE, BISP, SENSOR[0-1]
> > > >
> > > > There are several issues involved in this approach:
> > > >
> > > > * 'bisp_factor_table[]' describes the configuration of a regular 8-rates
> > > > divider, so its usage is redundant. Additionally, judging by the BISP
> > > > clock context, it is incomplete since it maps only 8 out of 12
> > > > possible entries.
> > > >
> > > > * The clocks mentioned above are not identical in terms of the available
> > > > rates, therefore cannot rely on the same factor table. Specifically,
> > > > BISP and SENSOR* are standard 12-rate dividers so their configuration
> > > > should rely on a proper clock div table, while VCE and VDE require a
> > > > factor table that is a actually a subset of the one needed for DE[1-2]
> > > > clocks.
> > > >
> > > > Let's fix this by implementing the following:
> > > >
> > > > * Add new factor tables 'de_factor_table' and 'hde_factor_table' to
> > > > properly handle DE[1-2], VCE and VDE clocks.
> > > >
> > > > * Add a common div table 'std12rate_div_table' for BISP and SENSOR[0-1]
> > > > clocks converted to OWL_COMP_DIV.
> > > >
> > > > * Drop the now unused 'bisp_factor_table[]'.
> > > >
> > >
> > > Nice!
> > >
> > > > Additionally, since SENSOR[0-1] are not gated, unset the OWL_GATE_HW
> > > > configuration and drop the CLK_IGNORE_UNUSED flag in their definitions.
> > > >
> > >
> > > No. You should not screen the functionality exposed by the hw, that's what the
> > > purpose of these CLK_ flags.
> >
> > I'm not sure I get this, or maybe I wasn't clear enough with my
> > explanation regarding the changes to SENSOR clocks: they are not gated
> > in hardware, hence the statement 'OWL_GATE_HW(CMU_DEVCLKEN0, 14, 0)'
> > was invalid and I replaced it with '{ 0 }'.
> >
>
> This clock is gated in hw as per the datasheet. Again, please don't make
> judgements based on the vendor code as it is not upto date with HW. I
> know it is silly but that's how things are...
Indeed, a newer datasheet states the clock is gated. I fixed the patch
accordingly in v2.
> > Additionally, I assumed the 'CLK_IGNORE_UNUSED' flag makes sense only
> > for the gated clocks. Do I miss something?
> >
>
> CLK_IGNORE_UNUSED is used by the clk framework to essentially skip
> gating the clocks which are turned ON by the bootloader and there is no
> other driver using it. But I think you can remove this flag because
> there is no reason to leave this specific clock to be ON always.
Thanks for the explanation, I kept the flag removed in v2.
Regards,
Cristi
> Thanks,
> Mani
>
> > > Other than that, this patch looks good to me.
> >
> > Thanks,
> > Cristi
> >
> > [...]
next prev parent reply other threads:[~2021-05-27 13:35 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-08 17:18 [PATCH 0/6] Improve clock support for Actions S500 SoC Cristian Ciocaltea
2021-03-08 17:18 ` [PATCH 1/6] clk: actions: Fix UART clock dividers on Owl " Cristian Ciocaltea
2021-03-16 3:50 ` Manivannan Sadhasivam
2021-03-08 17:18 ` [PATCH 2/6] clk: actions: Fix SD clocks factor table " Cristian Ciocaltea
2021-03-16 3:58 ` Manivannan Sadhasivam
2021-03-16 18:14 ` Cristian Ciocaltea
2021-05-26 10:07 ` Manivannan Sadhasivam
2021-05-27 13:27 ` Cristian Ciocaltea
2021-03-08 17:18 ` [PATCH 3/6] clk: actions: Fix bisp_factor_table based clocks " Cristian Ciocaltea
2021-03-16 4:17 ` Manivannan Sadhasivam
2021-03-16 18:37 ` Cristian Ciocaltea
2021-05-26 10:18 ` Manivannan Sadhasivam
2021-05-27 13:34 ` Cristian Ciocaltea [this message]
2021-03-08 17:18 ` [PATCH 4/6] clk: actions: Fix AHPPREDIV-H-AHB clock chain " Cristian Ciocaltea
2021-03-16 5:45 ` Manivannan Sadhasivam
2021-03-16 18:50 ` Cristian Ciocaltea
2021-05-26 10:12 ` Manivannan Sadhasivam
2021-05-27 13:45 ` Cristian Ciocaltea
2021-03-08 17:18 ` [PATCH 5/6] dt-bindings: clock: Add NIC and ETHERNET bindings for Actions " Cristian Ciocaltea
2021-03-16 22:00 ` Rob Herring
2021-03-08 17:18 ` [PATCH 6/6] clk: actions: Add NIC and ETHERNET clock support " Cristian Ciocaltea
2021-03-16 5:52 ` Manivannan Sadhasivam
2021-03-16 19:02 ` Cristian Ciocaltea
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:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210527133452.GB1300160@BV030612LT \
--to=cristian.ciocaltea@gmail.com \
--cc=afaerber@suse.de \
--cc=devicetree@vger.kernel.org \
--cc=edgar.righi@lsitec.org.br \
--cc=linux-actions@lists.infradead.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-clk@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=manivannan.sadhasivam@linaro.org \
--cc=mturquette@baylibre.com \
--cc=robh+dt@kernel.org \
--cc=sboyd@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* 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).