From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
To: Boris BREZILLON <b.brezillon@overkiz.com>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>,
Ludovic Desroches <ludovic.desroches@atmel.com>,
Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>,
Chris Ball <cjb@laptop.org>,
linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3 2/7] mmc: atmel-mci: prepare clk before calling enable
Date: Tue, 16 Jul 2013 17:13:24 +0200 [thread overview]
Message-ID: <20130716171324.7d483ada@skate> (raw)
In-Reply-To: <1373987208-24120-1-git-send-email-b.brezillon@overkiz.com>
Dear Boris BREZILLON,
On Tue, 16 Jul 2013 17:06:48 +0200, Boris BREZILLON wrote:
> buf = kmalloc(ATMCI_REGS_SIZE, GFP_KERNEL);
> if (!buf)
> @@ -389,9 +391,13 @@ static int atmci_regs_show(struct seq_file *s, void *v)
> * consistent.
> */
> spin_lock_bh(&host->lock);
> - clk_enable(host->mck);
> + ret = clk_prepare_enable(host->mck);
I am not very familiar with the spin_lock_bh() variant, but are you
sure we are allowed to sleep within a spin_lock_bh()-protected critical
section?
Remember that clk_prepare_enable() calls both ->prepare() and
->enable() for the clock, and ->prepare() is allowed to sleep, while
->enable() is guaranteed not to sleep.
Therefore, clk_prepare() is usually called at probe time, while
clk_enable() is called whenever enabling/disabling the clock is really
needed. So not all clk_enable() can transparently be converted into a
clk_prepare_enable().
Best regards,
Thomas
--
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com
WARNING: multiple messages have this Message-ID (diff)
From: thomas.petazzoni@free-electrons.com (Thomas Petazzoni)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v3 2/7] mmc: atmel-mci: prepare clk before calling enable
Date: Tue, 16 Jul 2013 17:13:24 +0200 [thread overview]
Message-ID: <20130716171324.7d483ada@skate> (raw)
In-Reply-To: <1373987208-24120-1-git-send-email-b.brezillon@overkiz.com>
Dear Boris BREZILLON,
On Tue, 16 Jul 2013 17:06:48 +0200, Boris BREZILLON wrote:
> buf = kmalloc(ATMCI_REGS_SIZE, GFP_KERNEL);
> if (!buf)
> @@ -389,9 +391,13 @@ static int atmci_regs_show(struct seq_file *s, void *v)
> * consistent.
> */
> spin_lock_bh(&host->lock);
> - clk_enable(host->mck);
> + ret = clk_prepare_enable(host->mck);
I am not very familiar with the spin_lock_bh() variant, but are you
sure we are allowed to sleep within a spin_lock_bh()-protected critical
section?
Remember that clk_prepare_enable() calls both ->prepare() and
->enable() for the clock, and ->prepare() is allowed to sleep, while
->enable() is guaranteed not to sleep.
Therefore, clk_prepare() is usually called at probe time, while
clk_enable() is called whenever enabling/disabling the clock is really
needed. So not all clk_enable() can transparently be converted into a
clk_prepare_enable().
Best regards,
Thomas
--
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com
next prev parent reply other threads:[~2013-07-16 15:13 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-16 15:03 [PATCH v3 0/7] ARM: at91: prepare transition to common clk framework Boris BREZILLON
2013-07-16 15:03 ` Boris BREZILLON
2013-07-16 15:05 ` [PATCH v3 1/7] ARM: at91/tc/clocksource: replace clk_enable/disable with clk_prepare_enable/disable_unprepare Boris BREZILLON
2013-07-16 15:05 ` Boris BREZILLON
2013-07-16 15:48 ` Daniel Lezcano
2013-07-16 15:48 ` Daniel Lezcano
2013-07-16 15:06 ` [PATCH v3 2/7] mmc: atmel-mci: prepare clk before calling enable Boris BREZILLON
2013-07-16 15:06 ` Boris BREZILLON
2013-07-16 15:13 ` Thomas Petazzoni [this message]
2013-07-16 15:13 ` Thomas Petazzoni
2013-07-16 15:49 ` boris brezillon
2013-07-16 15:49 ` boris brezillon
2013-07-16 17:13 ` Russell King - ARM Linux
2013-07-16 17:13 ` Russell King - ARM Linux
2013-07-16 15:08 ` [PATCH v3 3/7] at91/avr32/atmel_lcdfb: " Boris BREZILLON
2013-07-16 15:08 ` Boris BREZILLON
2013-07-16 15:08 ` Boris BREZILLON
2013-07-16 15:10 ` [PATCH v3 4/7] USB: gadget: atmel_usba: " Boris BREZILLON
2013-07-16 15:10 ` Boris BREZILLON
2013-07-16 15:16 ` [PATCH v3 5/7] spi: atmel: " Boris BREZILLON
2013-07-16 15:16 ` Boris BREZILLON
2013-07-17 8:10 ` Mark Brown
2013-07-17 8:10 ` Mark Brown
2013-07-16 15:22 ` [PATCH v3 6/7] USB: ohci-at91: add usb_clk for transition to common clk framework Boris BREZILLON
2013-07-16 15:22 ` Boris BREZILLON
2013-07-16 16:48 ` Alan Stern
2013-07-16 16:48 ` Alan Stern
2013-07-16 17:08 ` boris brezillon
2013-07-16 17:08 ` boris brezillon
2013-07-16 18:47 ` Alan Stern
2013-07-16 18:47 ` Alan Stern
2013-07-16 19:06 ` boris brezillon
2013-07-16 19:06 ` boris brezillon
2013-07-16 17:07 ` Russell King - ARM Linux
2013-07-16 17:07 ` Russell King - ARM Linux
2013-07-17 15:33 ` Alan Stern
2013-07-17 15:33 ` Alan Stern
2013-07-17 15:45 ` boris brezillon
2013-07-17 15:45 ` boris brezillon
2013-07-17 16:17 ` Alan Stern
2013-07-17 16:17 ` Alan Stern
2013-07-16 15:25 ` [PATCH v3 7/7] usb: gadget: at91_udc: " Boris BREZILLON
2013-07-16 15:25 ` Boris BREZILLON
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