From: Stephen Boyd <sboyd@codeaurora.org>
To: linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2] clk: let clk_disable() return immediately if clk is NULL or error
Date: Thu, 14 Apr 2016 00:33:41 +0000 [thread overview]
Message-ID: <20160414003341.GH14441@codeaurora.org> (raw)
In-Reply-To: <CAK7LNASW+D0B_k97r__AZeYDR5UqNPqn_j1aoQepHz-bGgV2ng@mail.gmail.com>
On 04/08, Masahiro Yamada wrote:
>
>
> This makes our driver programming life easier.
>
>
> For example, let's see drivers/tty/serial/8250/8250_of.c
>
>
> The "clock-frequency" DT property takes precedence over "clocks" property.
> So, it is valid to probe the driver with a NULL pointer for info->clk.
>
>
> if (of_property_read_u32(np, "clock-frequency", &clk)) {
>
> /* Get clk rate through clk driver if present */
> info->clk = devm_clk_get(&ofdev->dev, NULL);
> if (IS_ERR(info->clk)) {
> dev_warn(&ofdev->dev,
> "clk or clock-frequency not defined\n");
> return PTR_ERR(info->clk);
> }
>
> ret = clk_prepare_enable(info->clk);
> if (ret < 0)
> return ret;
>
> clk = clk_get_rate(info->clk);
> }
>
>
> As a result, we need to make sure the clk pointer is valid
> before calling clk_disable_unprepare().
>
>
> If we could support pointer checking in callees, we would be able to
> clean-up lots of clock consumers.
>
>
I'm not sure if you meant to use that example for the error
pointer case? It bails out if clk_get() returns an error pointer.
I'm all for a no-op in clk_disable()/unprepare() when the pointer
is NULL. But when it's an error pointer the driver should be
handling it and bail out before it would ever call enable/prepare
on it or disable/unprepare.
--
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project
WARNING: multiple messages have this Message-ID (diff)
From: Stephen Boyd <sboyd@codeaurora.org>
To: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: linux-clk@vger.kernel.org, Ralf Baechle <ralf@linux-mips.org>,
Michael Turquette <mturquette@baylibre.com>,
linux-mips@linux-mips.org, linux-sh@vger.kernel.org,
Haojian Zhuang <haojian.zhuang@gmail.com>,
Eric Miao <eric.y.miao@gmail.com>,
Hartley Sweeten <hsweeten@visionengravers.com>,
Greg Ungerer <gerg@uclinux.org>, Ryan Mallon <rmallon@gmail.com>,
Geert Uytterhoeven <geert@linux-m68k.org>,
Steven Miao <realmz6@gmail.com>,
Simon Horman <horms@verge.net.au>,
Wan ZongShun <mcuos.com@gmail.com>, Rich Felker <dalias@libc.org>,
Yoshinori Sato <ysato@users.sourceforge.jp>,
adi-buildroot-devel@lists.sourceforge.net,
Russell King <linux@arm.linux.org.uk>,
linux-m68k@vger.kernel.org,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-renesas-soc@vger.kernel.org,
Magnus Damm <magnus.damm@gmail.com>,
John Crispin <blogic@openwrt.org>
Subject: Re: [PATCH v2] clk: let clk_disable() return immediately if clk is NULL or error
Date: Wed, 13 Apr 2016 17:33:41 -0700 [thread overview]
Message-ID: <20160414003341.GH14441@codeaurora.org> (raw)
In-Reply-To: <CAK7LNASW+D0B_k97r__AZeYDR5UqNPqn_j1aoQepHz-bGgV2ng@mail.gmail.com>
On 04/08, Masahiro Yamada wrote:
>
>
> This makes our driver programming life easier.
>
>
> For example, let's see drivers/tty/serial/8250/8250_of.c
>
>
> The "clock-frequency" DT property takes precedence over "clocks" property.
> So, it is valid to probe the driver with a NULL pointer for info->clk.
>
>
> if (of_property_read_u32(np, "clock-frequency", &clk)) {
>
> /* Get clk rate through clk driver if present */
> info->clk = devm_clk_get(&ofdev->dev, NULL);
> if (IS_ERR(info->clk)) {
> dev_warn(&ofdev->dev,
> "clk or clock-frequency not defined\n");
> return PTR_ERR(info->clk);
> }
>
> ret = clk_prepare_enable(info->clk);
> if (ret < 0)
> return ret;
>
> clk = clk_get_rate(info->clk);
> }
>
>
> As a result, we need to make sure the clk pointer is valid
> before calling clk_disable_unprepare().
>
>
> If we could support pointer checking in callees, we would be able to
> clean-up lots of clock consumers.
>
>
I'm not sure if you meant to use that example for the error
pointer case? It bails out if clk_get() returns an error pointer.
I'm all for a no-op in clk_disable()/unprepare() when the pointer
is NULL. But when it's an error pointer the driver should be
handling it and bail out before it would ever call enable/prepare
on it or disable/unprepare.
--
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project
WARNING: multiple messages have this Message-ID (diff)
From: Stephen Boyd <sboyd@codeaurora.org>
To: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: linux-clk@vger.kernel.org, Ralf Baechle <ralf@linux-mips.org>,
Michael Turquette <mturquette@baylibre.com>,
linux-mips@linux-mips.org, linux-sh@vger.kernel.org,
Haojian Zhuang <haojian.zhuang@gmail.com>,
Eric Miao <eric.y.miao@gmail.com>,
Hartley Sweeten <hsweeten@visionengravers.com>,
Greg Ungerer <gerg@uclinux.org>, Ryan Mallon <rmallon@gmail.com>,
Geert Uytterhoeven <geert@linux-m68k.org>,
Steven Miao <realmz6@gmail.com>,
Simon Horman <horms@verge.net.au>,
Wan ZongShun <mcuos.com@gmail.com>, Rich Felker <dalias@libc.org>,
Yoshinori Sato <ysato@users.sourceforge.jp>,
adi-buildroot-devel@lists.sourceforge.net,
Russell King <linux@arm.linux.org.uk>,
linux-m68k@lists.linux-m68k.org,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-renesas-soc@vger.kernel.org,
Magnus Damm <magnus.damm@gmail.com>,
John Crispin <blogic@openwrt.org>
Subject: Re: [PATCH v2] clk: let clk_disable() return immediately if clk is NULL or error
Date: Wed, 13 Apr 2016 17:33:41 -0700 [thread overview]
Message-ID: <20160414003341.GH14441@codeaurora.org> (raw)
In-Reply-To: <CAK7LNASW+D0B_k97r__AZeYDR5UqNPqn_j1aoQepHz-bGgV2ng@mail.gmail.com>
On 04/08, Masahiro Yamada wrote:
>
>
> This makes our driver programming life easier.
>
>
> For example, let's see drivers/tty/serial/8250/8250_of.c
>
>
> The "clock-frequency" DT property takes precedence over "clocks" property.
> So, it is valid to probe the driver with a NULL pointer for info->clk.
>
>
> if (of_property_read_u32(np, "clock-frequency", &clk)) {
>
> /* Get clk rate through clk driver if present */
> info->clk = devm_clk_get(&ofdev->dev, NULL);
> if (IS_ERR(info->clk)) {
> dev_warn(&ofdev->dev,
> "clk or clock-frequency not defined\n");
> return PTR_ERR(info->clk);
> }
>
> ret = clk_prepare_enable(info->clk);
> if (ret < 0)
> return ret;
>
> clk = clk_get_rate(info->clk);
> }
>
>
> As a result, we need to make sure the clk pointer is valid
> before calling clk_disable_unprepare().
>
>
> If we could support pointer checking in callees, we would be able to
> clean-up lots of clock consumers.
>
>
I'm not sure if you meant to use that example for the error
pointer case? It bails out if clk_get() returns an error pointer.
I'm all for a no-op in clk_disable()/unprepare() when the pointer
is NULL. But when it's an error pointer the driver should be
handling it and bail out before it would ever call enable/prepare
on it or disable/unprepare.
--
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project
WARNING: multiple messages have this Message-ID (diff)
From: sboyd@codeaurora.org (Stephen Boyd)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2] clk: let clk_disable() return immediately if clk is NULL or error
Date: Wed, 13 Apr 2016 17:33:41 -0700 [thread overview]
Message-ID: <20160414003341.GH14441@codeaurora.org> (raw)
In-Reply-To: <CAK7LNASW+D0B_k97r__AZeYDR5UqNPqn_j1aoQepHz-bGgV2ng@mail.gmail.com>
On 04/08, Masahiro Yamada wrote:
>
>
> This makes our driver programming life easier.
>
>
> For example, let's see drivers/tty/serial/8250/8250_of.c
>
>
> The "clock-frequency" DT property takes precedence over "clocks" property.
> So, it is valid to probe the driver with a NULL pointer for info->clk.
>
>
> if (of_property_read_u32(np, "clock-frequency", &clk)) {
>
> /* Get clk rate through clk driver if present */
> info->clk = devm_clk_get(&ofdev->dev, NULL);
> if (IS_ERR(info->clk)) {
> dev_warn(&ofdev->dev,
> "clk or clock-frequency not defined\n");
> return PTR_ERR(info->clk);
> }
>
> ret = clk_prepare_enable(info->clk);
> if (ret < 0)
> return ret;
>
> clk = clk_get_rate(info->clk);
> }
>
>
> As a result, we need to make sure the clk pointer is valid
> before calling clk_disable_unprepare().
>
>
> If we could support pointer checking in callees, we would be able to
> clean-up lots of clock consumers.
>
>
I'm not sure if you meant to use that example for the error
pointer case? It bails out if clk_get() returns an error pointer.
I'm all for a no-op in clk_disable()/unprepare() when the pointer
is NULL. But when it's an error pointer the driver should be
handling it and bail out before it would ever call enable/prepare
on it or disable/unprepare.
--
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project
next prev parent reply other threads:[~2016-04-14 0:33 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-05 1:51 [PATCH v2] clk: let clk_disable() return immediately if clk is NULL or error Masahiro Yamada
2016-04-05 1:51 ` Masahiro Yamada
2016-04-05 1:51 ` Masahiro Yamada
2016-04-05 1:51 ` Masahiro Yamada
2016-04-08 0:33 ` Stephen Boyd
2016-04-08 0:33 ` Stephen Boyd
2016-04-08 0:33 ` Stephen Boyd
2016-04-08 0:33 ` Stephen Boyd
2016-04-08 1:52 ` Masahiro Yamada
2016-04-08 1:52 ` Masahiro Yamada
2016-04-08 1:52 ` Masahiro Yamada
2016-04-08 1:52 ` Masahiro Yamada
2016-04-08 1:52 ` Masahiro Yamada
2016-04-14 0:33 ` Stephen Boyd
2016-04-14 0:33 ` Stephen Boyd [this message]
2016-04-14 0:33 ` Stephen Boyd
2016-04-14 0:33 ` Stephen Boyd
2016-04-14 0:33 ` Stephen Boyd
2016-04-14 1:49 ` Masahiro Yamada
2016-04-14 1:49 ` Masahiro Yamada
2016-04-14 1:49 ` Masahiro Yamada
2016-04-14 1:49 ` Masahiro Yamada
2016-04-16 0:04 ` Stephen Boyd
2016-04-16 0:04 ` Stephen Boyd
2016-04-16 0:04 ` Stephen Boyd
2016-04-16 0:04 ` Stephen Boyd
2016-04-16 0:04 ` Stephen Boyd
2016-04-14 1:49 ` Masahiro Yamada
2016-04-08 10:06 ` Ralf Baechle
2016-04-08 10:06 ` Ralf Baechle
2016-04-08 10:06 ` Ralf Baechle
2016-04-08 10:06 ` Ralf Baechle
2016-04-08 11:15 ` Masahiro Yamada
2016-04-08 11:15 ` Masahiro Yamada
2016-04-08 11:15 ` Masahiro Yamada
2016-04-08 11:15 ` Masahiro Yamada
2016-04-14 0:40 ` Stephen Boyd
2016-04-14 0:40 ` Stephen Boyd
2016-04-14 0:40 ` Stephen Boyd
2016-04-14 0:40 ` Stephen Boyd
2016-04-08 0:33 ` Stephen Boyd
2016-04-05 1:51 Masahiro Yamada
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