From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Simon Horman <horms@verge.net.au>
Cc: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>,
Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
Michael Turquette <mturquette@baylibre.com>,
Stephen Boyd <sboyd@codeaurora.org>,
Geert Uytterhoeven <geert+renesas@glider.be>,
linux-clk <linux-clk@vger.kernel.org>
Subject: Re: [PATCH v2 2/4] clk: renesas: rcar-gen3-cpg: add spinlock
Date: Mon, 21 Jan 2019 14:40:33 +0100 [thread overview]
Message-ID: <CAMuHMdXdFw2s0-kVZYJkiJ8TSYZJ3G774oNFXob9U=MkaU3=qA@mail.gmail.com> (raw)
In-Reply-To: <20181214153332.47ukfkkgdrnsysmb@verge.net.au>
Hi Simon,
On Fri, Dec 14, 2018 at 4:33 PM Simon Horman <horms@verge.net.au> wrote:
> On Tue, Dec 04, 2018 at 10:49:44PM +0300, Sergei Shtylyov wrote:
> > Protect the CPG register read-modify-write sequence with a spinlock.
>
> Spinlocks are expensive, I think an explanation of why this is
> necessary would be worthwhile.
Some clock registers contain bits for multiple clocks.
Hence read-modify-write cycles on these registers should be protected
against concurrent accesses for multiple clocks.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
next prev parent reply other threads:[~2019-01-21 13:40 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-04 19:43 [PATCH v2 0/4] Renesas R8A77980 CPG/MSSR RPC clock support Sergei Shtylyov
2018-12-04 19:48 ` [PATCH v2 1/4] clk: renesas: rcar-gen3-cpg: factor out cpg_reg_modify() Sergei Shtylyov
2018-12-14 15:32 ` Simon Horman
2019-01-21 13:25 ` Geert Uytterhoeven
2018-12-04 19:49 ` [PATCH v2 2/4] clk: renesas: rcar-gen3-cpg: add spinlock Sergei Shtylyov
2018-12-14 15:33 ` Simon Horman
2019-01-21 13:40 ` Geert Uytterhoeven [this message]
2019-01-21 18:49 ` Sergei Shtylyov
2019-01-21 14:08 ` Geert Uytterhoeven
2018-12-04 19:51 ` [PATCH v2 3/4] clk: renesas: rcar-gen3-cpg: add RPC clocks Sergei Shtylyov
2019-01-21 14:17 ` Geert Uytterhoeven
2018-12-04 19:52 ` [PATCH v2 4/4] clk: renesas: r8a77980-cpg-mssr: " Sergei Shtylyov
2019-01-21 14:18 ` Geert Uytterhoeven
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