From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shubhrajyoti Subject: Re: [PATCHv5 1/3] OMAP: I2C: Reset support Date: Thu, 04 Aug 2011 11:55:12 +0530 Message-ID: <4E3A3B48.2050108@ti.com> References: <1311935813-8481-1-git-send-email-shubhrajyoti@ti.com> <1311935813-8481-2-git-send-email-shubhrajyoti@ti.com> <87sjpj75yq.fsf@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <87sjpj75yq.fsf-l0cyMroinI0@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Kevin Hilman Cc: linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, rnayak-l0cyMroinI0@public.gmane.org, balajitk-l0cyMroinI0@public.gmane.org, santosh.shilimkar-l0cyMroinI0@public.gmane.org List-Id: linux-i2c@vger.kernel.org On Wednesday 03 August 2011 04:53 AM, Kevin Hilman wrote: > Shubhrajyoti D writes: > >> Under some error conditions the i2c driver may do a reset. > ^ ^ > minor: extra whitespace > >> Adding a reset field and support in the platform. > s/platform/device-specific code/ > Yes will fix these. >> Signed-off-by: Shubhrajyoti D > That being said, omap_device_shutdown() should already do a clean > shutdown + reset for you, and i2c-omap.h already has a pointer for > ->device_shutdown() so a new device_reset() should not be needed. > > IOW, simply adding pdata->device_shutdown = omap_device_shutdown() > should work. i2C has a special reset sequence ie Disable -> reset -> enable -> Poll on reset done. This function is implemented in omap_i2c_reset. The omap_hwmod_reset calls -> _reset which calls ocp_softrest or custom reset if it is present.The latter is true for I2C. However I see that omap_device_shutdown -> _assert_hardreset However for I2c there doesnt seem to be a HW reset line. Am I missing something? > Kevin > >> --- >> arch/arm/plat-omap/i2c.c | 18 ++++++++++++++++++ >> include/linux/i2c-omap.h | 1 + >> 2 files changed, 19 insertions(+), 0 deletions(-) >> >> diff --git a/arch/arm/plat-omap/i2c.c b/arch/arm/plat-omap/i2c.c >> index 2388b8e..be36cac 100644 >> --- a/arch/arm/plat-omap/i2c.c >> +++ b/arch/arm/plat-omap/i2c.c >> @@ -146,6 +146,22 @@ static struct omap_device_pm_latency omap_i2c_latency[] = { >> .flags = OMAP_DEVICE_LATENCY_AUTO_ADJUST, >> }, >> }; >> +/** >> + * omap2_i2c_reset - reset the omap i2c module. >> + * @dev: struct device* >> + */ >> + >> +static int omap2_i2c_reset(struct device *dev) >> +{ >> + int r = 0; >> + struct platform_device *pdev = to_platform_device(dev); >> + struct omap_device *odev = to_omap_device(pdev); >> + struct omap_hwmod *oh; >> + >> + oh = odev->hwmods[0]; >> + r = omap_hwmod_reset(oh); >> + return r; >> +} >> >> static inline int omap2_i2c_add_bus(int bus_id) >> { >> @@ -187,6 +203,8 @@ static inline int omap2_i2c_add_bus(int bus_id) >> */ >> if (cpu_is_omap34xx()) >> pdata->set_mpu_wkup_lat = omap_pm_set_max_mpu_wakeup_lat_compat; >> + >> + pdata->device_reset = omap2_i2c_reset; >> od = omap_device_build(name, bus_id, oh, pdata, >> sizeof(struct omap_i2c_bus_platform_data), >> omap_i2c_latency, ARRAY_SIZE(omap_i2c_latency), 0); >> diff --git a/include/linux/i2c-omap.h b/include/linux/i2c-omap.h >> index 98ae49b..8aa91b6 100644 >> --- a/include/linux/i2c-omap.h >> +++ b/include/linux/i2c-omap.h >> @@ -38,6 +38,7 @@ struct omap_i2c_bus_platform_data { >> int (*device_enable) (struct platform_device *pdev); >> int (*device_shutdown) (struct platform_device *pdev); >> int (*device_idle) (struct platform_device *pdev); >> + int (*device_reset) (struct device *dev); >> }; >> >> #endif