From: Stephen Boyd <sboyd@kernel.org>
To: Luca Ceresoli <luca@lucaceresoli.net>, linux-clk@vger.kernel.org
Cc: Luca Ceresoli <luca@lucaceresoli.net>,
Michael Turquette <mturquette@baylibre.com>,
linux-kernel@vger.kernel.org, Adam Ford <aford173@gmail.com>
Subject: Re: [PATCH RESEND] clk: vc5: fix output disabling when enabling a FOD
Date: Tue, 08 Jun 2021 17:53:39 -0700 [thread overview]
Message-ID: <162320001952.1835121.12525475382527041110@swboyd.mtv.corp.google.com> (raw)
In-Reply-To: <20210527211647.1520720-1-luca@lucaceresoli.net>
Quoting Luca Ceresoli (2021-05-27 14:16:47)
> On 5P49V6965, when an output is enabled we enable the corresponding
> FOD. When this happens for the first time, and specifically when writing
> register VC5_OUT_DIV_CONTROL in vc5_clk_out_prepare(), all other outputs
> are stopped for a short time and then restarted.
>
> According to Renesas support this is intended: "The reason for that is VC6E
> has synced up all output function".
>
> This behaviour can be disabled at least on VersaClock 6E devices, of which
> only the 5P49V6965 is currently implemented by this driver. This requires
> writing bit 7 (bypass_sync{1..4}) in register 0x20..0x50. Those registers
> are named "Unused Factory Reserved Register", and the bits are documented
> as "Skip VDDO<N> verification", which does not clearly explain the relation
> to FOD sync. However according to Renesas support as well as my testing
> setting this bit does prevent disabling of all clock outputs when enabling
> a FOD.
>
> See "VersaClock ® 6E Family Register Descriptions and Programming Guide"
> (August 30, 2018), Table 116 "Power Up VDD check", page 58:
> https://www.renesas.com/us/en/document/mau/versaclock-6e-family-register-descriptions-and-programming-guide
>
> Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net>
> Reviewed-by: Adam Ford <aford173@gmail.com>
>
> ---
Applied to clk-next
prev parent reply other threads:[~2021-06-09 0:53 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-27 21:16 [PATCH RESEND] clk: vc5: fix output disabling when enabling a FOD Luca Ceresoli
2021-06-02 8:00 ` Stephen Boyd
2021-06-03 8:44 ` Luca Ceresoli
2021-06-03 20:07 ` Stephen Boyd
2021-06-03 21:06 ` Luca Ceresoli
2021-06-09 0:53 ` Stephen Boyd [this message]
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=162320001952.1835121.12525475382527041110@swboyd.mtv.corp.google.com \
--to=sboyd@kernel.org \
--cc=aford173@gmail.com \
--cc=linux-clk@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=luca@lucaceresoli.net \
--cc=mturquette@baylibre.com \
/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).