From: "A.s. Dong" <aisheng.dong@nxp.com>
To: Stephen Boyd <sboyd@kernel.org>, Sascha Hauer <s.hauer@pengutronix.de>
Cc: "linux-clk@vger.kernel.org" <linux-clk@vger.kernel.org>,
"mturquette@baylibre.com" <mturquette@baylibre.com>,
dl-linux-imx <linux-imx@nxp.com>,
"kernel@pengutronix.de" <kernel@pengutronix.de>,
Fabio Estevam <fabio.estevam@nxp.com>,
"shawnguo@kernel.org" <shawnguo@kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: RE: [PATCH V4 05/11] clk: imx: scu: add scu clock gate
Date: Wed, 17 Oct 2018 07:28:44 +0000 [thread overview]
Message-ID: <AM0PR04MB4211CA6F8AF1A312A516DB0180FF0@AM0PR04MB4211.eurprd04.prod.outlook.com> (raw)
In-Reply-To: <153972471150.5275.14761857440358508106@swboyd.mtv.corp.google.com>
> From: Stephen Boyd [mailto:sboyd@kernel.org]
> Sent: Wednesday, October 17, 2018 5:19 AM
[...]
> > " Drivers don't need to manually protect resources shared between the
> > operations of one group, regardless of whether those resources are
> > shared by multiple clocks or not. However, access to resources that
> > are shared between operations of the two groups needs to be protected by
> the drivers."
> >
> > Do you think it's okay to drop it?
> >
>
> No it's not OK. We prefer that clk drivers don't assume the global locks in the
> clk framework are going to protect them from concurrent access to the same
> resource between different clks. Drivers can assume that a clk op won't be
> called in parallel for the same clk, but they shouldn't assume that everything is
> protected otherwise. If they did, we would have to go find all the drivers that
> make this assumption and then fix them when we eventually split the lock into
> smaller pieces.
>
> Long story short, if you have something shared (i.e. a register) and you plan to
> write to it and read from it for multiple clks, add a lock around it.
Okay, got it. Appreciated for the detailed explanation.
Regards
Dong Aisheng
WARNING: multiple messages have this Message-ID (diff)
From: aisheng.dong@nxp.com (A.s. Dong)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH V4 05/11] clk: imx: scu: add scu clock gate
Date: Wed, 17 Oct 2018 07:28:44 +0000 [thread overview]
Message-ID: <AM0PR04MB4211CA6F8AF1A312A516DB0180FF0@AM0PR04MB4211.eurprd04.prod.outlook.com> (raw)
In-Reply-To: <153972471150.5275.14761857440358508106@swboyd.mtv.corp.google.com>
> From: Stephen Boyd [mailto:sboyd at kernel.org]
> Sent: Wednesday, October 17, 2018 5:19 AM
[...]
> > " Drivers don't need to manually protect resources shared between the
> > operations of one group, regardless of whether those resources are
> > shared by multiple clocks or not. However, access to resources that
> > are shared between operations of the two groups needs to be protected by
> the drivers."
> >
> > Do you think it's okay to drop it?
> >
>
> No it's not OK. We prefer that clk drivers don't assume the global locks in the
> clk framework are going to protect them from concurrent access to the same
> resource between different clks. Drivers can assume that a clk op won't be
> called in parallel for the same clk, but they shouldn't assume that everything is
> protected otherwise. If they did, we would have to go find all the drivers that
> make this assumption and then fix them when we eventually split the lock into
> smaller pieces.
>
> Long story short, if you have something shared (i.e. a register) and you plan to
> write to it and read from it for multiple clks, add a lock around it.
Okay, got it. Appreciated for the detailed explanation.
Regards
Dong Aisheng
next prev parent reply other threads:[~2018-10-17 7:28 UTC|newest]
Thread overview: 84+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-14 8:07 [PATCH V4 00/11] clk: imx: add imx8qxp clock support A.s. Dong
2018-10-14 8:07 ` A.s. Dong
2018-10-14 8:07 ` [PATCH V4 01/11] clk: imx: add configuration option for mmio clks A.s. Dong
2018-10-14 8:07 ` A.s. Dong
2018-10-14 8:07 ` [PATCH V4 02/11] clk: imx: scu: add scu clock common part A.s. Dong
2018-10-14 8:07 ` A.s. Dong
2018-10-16 21:31 ` Stephen Boyd
2018-10-16 21:31 ` Stephen Boyd
2018-10-17 9:11 ` A.s. Dong
2018-10-17 9:11 ` A.s. Dong
2018-10-17 15:07 ` Stephen Boyd
2018-10-17 15:07 ` Stephen Boyd
2018-10-17 15:27 ` A.s. Dong
2018-10-17 15:27 ` A.s. Dong
2018-10-14 8:07 ` [PATCH V4 03/11] clk: imx: scu: add scu clock divider A.s. Dong
2018-10-14 8:07 ` A.s. Dong
2018-10-16 21:26 ` Stephen Boyd
2018-10-16 21:26 ` Stephen Boyd
2018-10-17 8:56 ` A.s. Dong
2018-10-17 8:56 ` A.s. Dong
2018-10-17 15:17 ` Stephen Boyd
2018-10-17 15:17 ` Stephen Boyd
2018-10-17 15:45 ` A.s. Dong
2018-10-17 15:45 ` A.s. Dong
2018-10-17 16:05 ` Stephen Boyd
2018-10-17 16:05 ` Stephen Boyd
2018-10-18 2:35 ` A.s. Dong
2018-10-18 2:35 ` A.s. Dong
2018-10-14 8:07 ` [PATCH V4 04/11] clk: imx: scu: add scu clock gpr divider A.s. Dong
2018-10-14 8:07 ` A.s. Dong
2018-10-16 21:27 ` Stephen Boyd
2018-10-16 21:27 ` Stephen Boyd
2018-10-17 9:03 ` A.s. Dong
2018-10-17 9:03 ` A.s. Dong
2018-10-17 15:17 ` Stephen Boyd
2018-10-17 15:17 ` Stephen Boyd
2018-10-14 8:07 ` [PATCH V4 05/11] clk: imx: scu: add scu clock gate A.s. Dong
2018-10-14 8:07 ` A.s. Dong
2018-10-15 7:32 ` Sascha Hauer
2018-10-15 7:32 ` Sascha Hauer
2018-10-15 9:17 ` A.s. Dong
2018-10-15 9:17 ` A.s. Dong
2018-10-15 9:53 ` Sascha Hauer
2018-10-15 9:53 ` Sascha Hauer
2018-10-15 15:30 ` A.s. Dong
2018-10-15 15:30 ` A.s. Dong
2018-10-16 21:18 ` Stephen Boyd
2018-10-16 21:18 ` Stephen Boyd
2018-10-17 7:28 ` A.s. Dong [this message]
2018-10-17 7:28 ` A.s. Dong
2018-10-14 8:07 ` [PATCH V4 06/11] clk: imx: scu: add scu clock gpr gate A.s. Dong
2018-10-14 8:07 ` A.s. Dong
2018-10-14 8:08 ` [PATCH V4 07/11] clk: imx: scu: add scu clock mux A.s. Dong
2018-10-14 8:08 ` A.s. Dong
2018-10-14 8:08 ` [PATCH V4 08/11] clk: imx: scu: add scu clock gpr mux A.s. Dong
2018-10-14 8:08 ` A.s. Dong
2018-10-16 21:30 ` Stephen Boyd
2018-10-16 21:30 ` Stephen Boyd
2018-10-17 9:07 ` A.s. Dong
2018-10-17 9:07 ` A.s. Dong
2018-10-17 15:18 ` Stephen Boyd
2018-10-17 15:18 ` Stephen Boyd
2018-10-14 8:08 ` [PATCH V4 09/11] clk: imx: add common imx_clk_hw_fixed functions A.s. Dong
2018-10-14 8:08 ` A.s. Dong
2018-10-16 21:32 ` Stephen Boyd
2018-10-16 21:32 ` Stephen Boyd
2018-10-17 9:21 ` A.s. Dong
2018-10-17 9:21 ` A.s. Dong
2018-10-17 15:18 ` Stephen Boyd
2018-10-17 15:18 ` Stephen Boyd
2018-10-14 8:08 ` [PATCH V4 10/11] clk: imx: add imx_check_clk_hws helper function A.s. Dong
2018-10-14 8:08 ` A.s. Dong
2018-10-16 21:34 ` Stephen Boyd
2018-10-16 21:34 ` Stephen Boyd
2018-10-17 9:24 ` A.s. Dong
2018-10-17 9:24 ` A.s. Dong
2018-10-14 8:08 ` [PATCH V4 11/11] clk: imx: add imx8qxp clk driver A.s. Dong
2018-10-14 8:08 ` A.s. Dong
2018-10-16 21:38 ` Stephen Boyd
2018-10-16 21:38 ` Stephen Boyd
2018-10-17 9:43 ` A.s. Dong
2018-10-17 9:43 ` A.s. Dong
2018-10-17 15:20 ` Stephen Boyd
2018-10-17 15:20 ` Stephen Boyd
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