From mboxrd@z Thu Jan 1 00:00:00 1970 From: Oleksandr Dmytryshyn Subject: Re: [PATCH v2 1/1] i2c: omap: correct usage of the interrupt enable register Date: Fri, 31 May 2013 11:19:08 +0300 Message-ID: <51A85CFC.2000904@ti.com> References: <1369929379-19165-1-git-send-email-oleksandr.dmytryshyn@ti.com> <1369929379-19165-2-git-send-email-oleksandr.dmytryshyn@ti.com> <87vc604dr9.fsf@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <87vc604dr9.fsf-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Kevin Hilman 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 On 05/30/2013 07:46 PM, Kevin Hilman wrote: > 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? Yes, this has been working up until now because we've 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. I'll rename this mask in the patch-set v3 > > Kevin > -- Best regards, Oleksandr Dmytryshyn | OMAP4 Platform GlobalLogic Inc. | Innovation by Design