From: Masahiro Yamada <yamada.masahiro@socionext.com>
To: linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2] clk: let clk_disable() return immediately if clk is NULL or error
Date: Fri, 08 Apr 2016 01:52:57 +0000 [thread overview]
Message-ID: <CAK7LNASW+D0B_k97r__AZeYDR5UqNPqn_j1aoQepHz-bGgV2ng@mail.gmail.com> (raw)
In-Reply-To: <20160408003328.GA14441@codeaurora.org>
Hi Stephen,
2016-04-08 9:33 GMT+09:00 Stephen Boyd <sboyd@codeaurora.org>:
> On 04/05, Masahiro Yamada wrote:
>> The clk_disable() in the common clock framework (drivers/clk/clk.c)
>> returns immediately if a given clk is NULL or an error pointer. It
>> allows clock consumers to call clk_disable() without IS_ERR_OR_NULL
>> checking if drivers are only used with the common clock framework.
>>
>> Unfortunately, NULL/error checking is missing from some of non-common
>> clk_disable() implementations. This prevents us from completely
>> dropping NULL/error checking from callers. Let's make it tree-wide
>> consistent by adding IS_ERR_OR_NULL(clk) to all callees.
>>
>> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
>> Acked-by: Greg Ungerer <gerg@uclinux.org>
>> Acked-by: Wan Zongshun <mcuos.com@gmail.com>
>> ---
>>
>> Stephen,
>>
>> This patch has been unapplied for a long time.
>>
>> Please let me know if there is something wrong with this patch.
>>
>
> I'm mostly confused why we wouldn't want to encourage people to
> call clk_disable or unprepare on a clk that's an error pointer.
> Typically an error pointer should be dealt with, instead of
> silently ignored, so why wasn't it dealt with by passing it up
> the probe() path?
>
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.
--
Best Regards
Masahiro Yamada
WARNING: multiple messages have this Message-ID (diff)
From: Masahiro Yamada <yamada.masahiro@socionext.com>
To: Stephen Boyd <sboyd@codeaurora.org>
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: Fri, 8 Apr 2016 10:52:57 +0900 [thread overview]
Message-ID: <CAK7LNASW+D0B_k97r__AZeYDR5UqNPqn_j1aoQepHz-bGgV2ng@mail.gmail.com> (raw)
In-Reply-To: <20160408003328.GA14441@codeaurora.org>
Hi Stephen,
2016-04-08 9:33 GMT+09:00 Stephen Boyd <sboyd@codeaurora.org>:
> On 04/05, Masahiro Yamada wrote:
>> The clk_disable() in the common clock framework (drivers/clk/clk.c)
>> returns immediately if a given clk is NULL or an error pointer. It
>> allows clock consumers to call clk_disable() without IS_ERR_OR_NULL
>> checking if drivers are only used with the common clock framework.
>>
>> Unfortunately, NULL/error checking is missing from some of non-common
>> clk_disable() implementations. This prevents us from completely
>> dropping NULL/error checking from callers. Let's make it tree-wide
>> consistent by adding IS_ERR_OR_NULL(clk) to all callees.
>>
>> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
>> Acked-by: Greg Ungerer <gerg@uclinux.org>
>> Acked-by: Wan Zongshun <mcuos.com@gmail.com>
>> ---
>>
>> Stephen,
>>
>> This patch has been unapplied for a long time.
>>
>> Please let me know if there is something wrong with this patch.
>>
>
> I'm mostly confused why we wouldn't want to encourage people to
> call clk_disable or unprepare on a clk that's an error pointer.
> Typically an error pointer should be dealt with, instead of
> silently ignored, so why wasn't it dealt with by passing it up
> the probe() path?
>
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.
--
Best Regards
Masahiro Yamada
WARNING: multiple messages have this Message-ID (diff)
From: Masahiro Yamada <yamada.masahiro@socionext.com>
To: Stephen Boyd <sboyd@codeaurora.org>
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: Fri, 8 Apr 2016 10:52:57 +0900 [thread overview]
Message-ID: <CAK7LNASW+D0B_k97r__AZeYDR5UqNPqn_j1aoQepHz-bGgV2ng@mail.gmail.com> (raw)
In-Reply-To: <20160408003328.GA14441@codeaurora.org>
Hi Stephen,
2016-04-08 9:33 GMT+09:00 Stephen Boyd <sboyd@codeaurora.org>:
> On 04/05, Masahiro Yamada wrote:
>> The clk_disable() in the common clock framework (drivers/clk/clk.c)
>> returns immediately if a given clk is NULL or an error pointer. It
>> allows clock consumers to call clk_disable() without IS_ERR_OR_NULL
>> checking if drivers are only used with the common clock framework.
>>
>> Unfortunately, NULL/error checking is missing from some of non-common
>> clk_disable() implementations. This prevents us from completely
>> dropping NULL/error checking from callers. Let's make it tree-wide
>> consistent by adding IS_ERR_OR_NULL(clk) to all callees.
>>
>> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
>> Acked-by: Greg Ungerer <gerg@uclinux.org>
>> Acked-by: Wan Zongshun <mcuos.com@gmail.com>
>> ---
>>
>> Stephen,
>>
>> This patch has been unapplied for a long time.
>>
>> Please let me know if there is something wrong with this patch.
>>
>
> I'm mostly confused why we wouldn't want to encourage people to
> call clk_disable or unprepare on a clk that's an error pointer.
> Typically an error pointer should be dealt with, instead of
> silently ignored, so why wasn't it dealt with by passing it up
> the probe() path?
>
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.
--
Best Regards
Masahiro Yamada
WARNING: multiple messages have this Message-ID (diff)
From: yamada.masahiro@socionext.com (Masahiro Yamada)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2] clk: let clk_disable() return immediately if clk is NULL or error
Date: Fri, 8 Apr 2016 10:52:57 +0900 [thread overview]
Message-ID: <CAK7LNASW+D0B_k97r__AZeYDR5UqNPqn_j1aoQepHz-bGgV2ng@mail.gmail.com> (raw)
In-Reply-To: <20160408003328.GA14441@codeaurora.org>
Hi Stephen,
2016-04-08 9:33 GMT+09:00 Stephen Boyd <sboyd@codeaurora.org>:
> On 04/05, Masahiro Yamada wrote:
>> The clk_disable() in the common clock framework (drivers/clk/clk.c)
>> returns immediately if a given clk is NULL or an error pointer. It
>> allows clock consumers to call clk_disable() without IS_ERR_OR_NULL
>> checking if drivers are only used with the common clock framework.
>>
>> Unfortunately, NULL/error checking is missing from some of non-common
>> clk_disable() implementations. This prevents us from completely
>> dropping NULL/error checking from callers. Let's make it tree-wide
>> consistent by adding IS_ERR_OR_NULL(clk) to all callees.
>>
>> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
>> Acked-by: Greg Ungerer <gerg@uclinux.org>
>> Acked-by: Wan Zongshun <mcuos.com@gmail.com>
>> ---
>>
>> Stephen,
>>
>> This patch has been unapplied for a long time.
>>
>> Please let me know if there is something wrong with this patch.
>>
>
> I'm mostly confused why we wouldn't want to encourage people to
> call clk_disable or unprepare on a clk that's an error pointer.
> Typically an error pointer should be dealt with, instead of
> silently ignored, so why wasn't it dealt with by passing it up
> the probe() path?
>
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.
--
Best Regards
Masahiro Yamada
next prev parent reply other threads:[~2016-04-08 1:52 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 [this message]
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
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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