From: santosh.shilimkar@ti•com (Santosh Shilimkar)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v2 4/7] i2c: omap: in case of VERSION_2 read IRQSTATUS_RAW but write to IRQSTATUS
Date: Thu, 25 Oct 2012 18:36:01 +0530 [thread overview]
Message-ID: <50893939.3060302@ti.com> (raw)
In-Reply-To: <20121025125249.GK21217@arwen.pp.htv.fi>
On Thursday 25 October 2012 06:22 PM, Felipe Balbi wrote:
> Hi,
>
> On Thu, Oct 25, 2012 at 06:23:57PM +0530, Santosh Shilimkar wrote:
>> On Thursday 25 October 2012 05:55 PM, Felipe Balbi wrote:
>>> on OMAP4+ we want to read IRQSTATUS_RAW register,
>>> instead of IRQSTATUS. The reason being that IRQSTATUS
>>> will only contain the bits which were enabled on
>>> IRQENABLE_SET and that will break when we need to
>>> poll for a certain bit which wasn't enabled as an
>>> IRQ source.
>>>
>>> One such case is after we finish converting to
>>> deferred stop bit, we will have to poll for ARDY
>>> bit before returning control for the client driver
>>> in order to prevent us from trying to start a
>>> transfer on a bus which is already busy.
>>>
>>> Note, however, that omap-i2c.c needs a big rework
>>> on register definition and register access. Such
>>> work will be done in a separate series of patches.
>>>
>>> Cc: Benoit Cousson <b-cousson@ti•com>
>>> Signed-off-by: Felipe Balbi <balbi@ti•com>
>>> ---
>>> drivers/i2c/busses/i2c-omap.c | 12 +++++++++++-
>>> 1 file changed, 11 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
>>> index b004126..20f9ad6 100644
>>> --- a/drivers/i2c/busses/i2c-omap.c
>>> +++ b/drivers/i2c/busses/i2c-omap.c
>>> @@ -271,8 +271,18 @@ static inline void omap_i2c_write_reg(struct omap_i2c_dev *i2c_dev,
>>>
>>> static inline u16 omap_i2c_read_reg(struct omap_i2c_dev *i2c_dev, int reg)
>>> {
>>> - return __raw_readw(i2c_dev->base +
>>> + /* if we are OMAP_I2C_IP_VERSION_2, we need to read from
>>> + * IRQSTATUS_RAW, but write to IRQSTATUS
>>> + */
>>> + if ((i2c_dev->dtrev == OMAP_I2C_IP_VERSION_2) &&
>>> + (reg == OMAP_I2C_STAT_REG)) {
>> Doing this check on every I2C register read seems to
>> expensive to me. Can you not sort this in init with some offset
>> which can be 0 or non zero ? Sorry in case this is already dicussed.
>
> could be. I didn't go that route because I'm planning a complete rewrite
> of all register accesses. The way it's done today is completely broken
> and already expensive (with reg_shift and different map tables and so
> on).
>
> If it's really a big of a deal, I can try to find another way, maybe
> just adding omap_i2c_read_stat() and limit the version check just to
> I2C_STAT reads would do it for now...
>
Its a hot path since you read many I2C register reads, so getting
rid of that additional check will be good.
next prev parent reply other threads:[~2012-10-25 13:06 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-22 9:46 [PATCH 0/8] I2C patches for v3.8 merge window Felipe Balbi
2012-10-22 9:46 ` [PATCH 1/8] i2c: omap: no need to access platform_device Felipe Balbi
2012-10-22 9:46 ` [PATCH 2/8] i2c: omap: reorder exit path of omap_i2c_xfer_msg() Felipe Balbi
2012-10-25 11:40 ` Shubhrajyoti Datta
2012-10-25 12:01 ` Felipe Balbi
2012-10-22 9:46 ` [PATCH 3/8] i2c: omap: fix error checking Felipe Balbi
2012-10-24 14:41 ` Michael Trimarchi
2012-10-25 10:10 ` Felipe Balbi
2012-10-25 10:33 ` Michael Trimarchi
2012-10-25 10:48 ` Felipe Balbi
2012-10-22 9:46 ` [PATCH 4/8] i2c: omap: also complete() when stat becomes zero Felipe Balbi
2012-10-22 9:46 ` [PATCH 5/8] i2c: omap: introduce and use OMAP_I2C_IP_VERSION_3 Felipe Balbi
2012-10-22 12:27 ` Benoit Cousson
2012-10-22 12:28 ` Felipe Balbi
2012-10-22 13:05 ` Benoit Cousson
2012-10-22 13:09 ` Felipe Balbi
2012-10-22 13:18 ` [PATCH v2 5/8] i2c: omap: in case of VERSION_2 read IRQSTATUS_RAW but write to IRQSTATUS Felipe Balbi
2012-10-22 9:46 ` [PATCH 6/8] i2c: omap: wait for transfer completion before sending STP bit Felipe Balbi
2012-10-22 9:46 ` [PATCH 7/8] i2c: add 'transferred' field to struct i2c_msg Felipe Balbi
2012-10-25 12:57 ` Jean Delvare
2012-10-25 13:14 ` Russell King - ARM Linux
2012-10-25 13:42 ` Jean Delvare
2012-10-25 13:46 ` Russell King - ARM Linux
2012-10-25 13:56 ` Jean Delvare
2012-10-25 14:18 ` Russell King - ARM Linux
2012-10-27 14:32 ` Jean Delvare
2012-10-27 16:40 ` Al Viro
2012-10-27 17:02 ` Al Viro
2012-10-27 17:10 ` Al Viro
2012-10-27 19:03 ` Jean Delvare
2012-10-27 17:25 ` Russell King - ARM Linux
2012-10-22 9:46 ` [PATCH 8/8] i2c: omap: implement handling for 'transferred' bytes Felipe Balbi
2012-10-22 13:30 ` [PATCH 0/8] I2C patches for v3.8 merge window Felipe Balbi
2012-10-22 14:06 ` Shubhrajyoti Datta
2012-10-22 14:06 ` Felipe Balbi
2012-10-22 15:02 ` Shubhrajyoti
2012-11-14 16:58 ` Wolfram Sang
2012-10-25 12:25 ` [PATCH v2 0/7] " Felipe Balbi
2012-10-25 12:25 ` [PATCH v2 1/7] i2c: omap: no need to access platform_device Felipe Balbi
2012-10-25 12:41 ` Santosh Shilimkar
2012-10-25 12:25 ` [PATCH v2 2/7] i2c: omap: reorder exit path of omap_i2c_xfer_msg() Felipe Balbi
2012-10-25 12:42 ` Santosh Shilimkar
2012-10-25 12:40 ` Felipe Balbi
2012-10-25 12:53 ` Lothar Waßmann
2012-10-25 12:25 ` [PATCH v2 3/7] i2c: omap: also complete() when stat becomes zero Felipe Balbi
2012-10-25 12:43 ` Santosh Shilimkar
2012-10-25 12:39 ` Felipe Balbi
2012-10-25 12:25 ` [PATCH v2 4/7] i2c: omap: in case of VERSION_2 read IRQSTATUS_RAW but write to IRQSTATUS Felipe Balbi
2012-10-25 12:53 ` Santosh Shilimkar
2012-10-25 12:52 ` Felipe Balbi
2012-10-25 13:06 ` Santosh Shilimkar [this message]
2012-10-25 12:25 ` [PATCH v2 5/7] i2c: omap: wait for transfer completion before sending STP bit Felipe Balbi
2012-10-25 12:32 ` Felipe Balbi
2012-10-25 12:34 ` [PATCH v3 " Felipe Balbi
2012-10-25 13:01 ` [PATCH v2 " Santosh Shilimkar
2012-10-25 14:15 ` Felipe Balbi
2012-10-25 12:25 ` [PATCH v2 6/7] i2c: add 'transferred' field to struct i2c_msg Felipe Balbi
2012-10-25 12:25 ` [PATCH v2 7/7] i2c: omap: implement handling for 'transferred' bytes Felipe Balbi
2012-10-27 18:55 ` Paul Walmsley
2012-11-05 8:10 ` [PATCH v2 0/7] I2C patches for v3.8 merge window Felipe Balbi
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