From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kevin Hilman Subject: Re: [PATCH v2 1/1] i2c: omap: correct usage of the interrupt enable register Date: Thu, 30 May 2013 09:46:18 -0700 Message-ID: <87vc604dr9.fsf@linaro.org> References: <1369929379-19165-1-git-send-email-oleksandr.dmytryshyn@ti.com> <1369929379-19165-2-git-send-email-oleksandr.dmytryshyn@ti.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: In-Reply-To: <1369929379-19165-2-git-send-email-oleksandr.dmytryshyn-l0cyMroinI0@public.gmane.org> (Oleksandr Dmytryshyn's message of "Thu, 30 May 2013 18:56:19 +0300") Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Oleksandr Dmytryshyn Cc: Tony Lindgren , Wolfram Sang , linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-i2c@vger.kernel.org Oleksandr Dmytryshyn writes: > If the i2c controller during suspend will generate an interrupt, it > can lead to unpredictable behaviour in the kernel. > > Based on the logic of the kernel code interrupts from i2c should be > prohibited during suspend. Kernel writes 0 to the I2C_IE register in > the omap_i2c_runtime_suspend() function. In the other side kernel > writes saved interrupt flags to the I2C_IE register in > omap_i2c_runtime_resume() function. I.e. interrupts should be disabled > during suspend. > > This works for chips with version1 registers scheme. Interrupts are > disabled during suspend. For chips with version2 scheme registers > writting 0 to the I2C_IE register does nothing (because now the > I2C_IRQENABLE_SET register is located at this address). This register > is used to enable interrupts. For disabling interrupts > I2C_IRQENABLE_CLR register should be used. > > Because the registers I2C_IRQENABLE_SET and I2C_IE have the same > addresses, the interrupt enabling procedure is unchanged. > > Signed-off-by: Oleksandr Dmytryshyn Much better, but still doesn't explain how/why this has been working up until now. Have we just been lucky? > --- > drivers/i2c/busses/i2c-omap.c | 15 +++++++++++---- > 1 file changed, 11 insertions(+), 4 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c > index e02f9e3..2419899 100644 > --- a/drivers/i2c/busses/i2c-omap.c > +++ b/drivers/i2c/busses/i2c-omap.c > @@ -180,6 +180,8 @@ enum { > #define I2C_OMAP_ERRATA_I207 (1 << 0) > #define I2C_OMAP_ERRATA_I462 (1 << 1) > > +#define OMAP_I2C_INTERRUPTS_MASK 0x6FFF To be more clear, this should probably have v2 in the name. Kevin