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Although unlikely, it is remotely possible for an i2c command to need
more than 200ms complete. Unlike smbus, i2c devices can clock stretch
for an unspecified amount of time. The longest time I've seen
specified for a device is 144ms (bq27541 battery gas), but one could
imagine a device taking a bit slower. 1 second "ought to be enough for
anyone."
The above is not the only justifcation for going above 200ms for a
timeout, though. It turns out that if you've got a large number of
printks going out to a serial console, interrupts on a CPU can be
disabled for hundreds of milliseconds. That's not a great situation to
be in to start with (maybe we should put a cap in vprintk_emit()) but
it's pretty annoying to start seeing unexplained i2c timeouts.
Note that to understand why we can timeout when printk has interrupts
disabled, you need to understand that on current Linux ARM kernels
interrupts are routed to a single CPU in a multicore system. Thus,
you can get:
1. CPU1 is running rk3x_i2c_xfer()
2. CPU0 calls vprintk_emit(), which disables all IRQs on CPU0.
3. I2C interrupt is ready but is set to only run on CPU0, where IRQs
are disabled.
4. CPU1 timeout expires. I2C interrupt is still ready, but CPU0 is
still sitting in the same vprintk_emit()
5. CPU1 sees that no interrupt happened in 200ms, so timeout.
A normal system shouldn't see i2c timeouts anyway, so increasing the
timeout should help people debugging without hurting other people
excessively.
Signed-off-by: Doug Anderson <dianders@chromium.org>
Tested-by: Caesar Wang <wxt@rock-chips.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
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master_xfer() method should return number of i2c messages transferred,
but on Rockchip we were usually returning just 1, which caused trouble
with users that actually check number of transferred messages vs.
checking for negative error codes.
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Cc: stable@kernel.org
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On Rockchip I2C the controller drops SDA low slightly too soon to meet
the "repeated start" requirements.
>From my own experimentation over a number of rates:
- controller appears to drop SDA at .875x (7/8) programmed clk high.
- controller appears to keep SCL high for 2x programmed clk high.
The first rule isn't enough to meet tSU;STA requirements in
Standard-mode on the system I tested on. The second rule is probably
enough to meet tHD;STA requirements in nearly all cases (especially
after accounting for the first), but it doesn't hurt to account for it
anyway just in case.
Even though the repeated start requirement only need to be accounted
for during a small part of the transfer, we'll adjust the timings for
the whole transfer to meet it. I believe that adjusting the timings
in just the right place to switch things up for repeated start would
require several extra interrupts and that doesn't seem terribly worth
it.
With this change and worst case rise/fall times, I see 100kHz i2c
going to ~85kHz. With slightly optimized rise/fall (800ns / 50ns) I
see i2c going to ~89kHz. Fast-mode isn't affected much because
tSU;STA is shorter relative to tHD;STA there.
As part of this change we needed to account for the SDA falling time.
The specification indicates that this should be the same, but we'll
follow Designware's lead and add a binding. Note that we deviate from
Designware and assign the default SDA falling time to be the same as
the SCL falling time, which is incredibly likely.
Signed-off-by: Doug Anderson <dianders@chromium.org>
[wsa: rebased to i2c/for-next]
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
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The number of clock cycles to be written into the CLKDIV register
that determines the I2C clk high phase includes the rise time.
So to meet the timing requirements defined in the I2C specification
which defines the minimal time SCL has to be high, the rise time
has to taken into account. The same applies to the low phase with
falling time.
In my test on RK3288-Pink2 board, which is not an upstream board yet,
if external pull-up resistor is 4.7K, rise_ns is about 700ns.
So the measured high_ns is about 3900ns, which is less than 4000ns
(the minimum high_ns in I2C specification for Standard-mode).
To fix this bug min_low_ns should include fall time and min_high_ns
should include rise time.
This patch merged the patch from chromium project which can get the
rise and fall times for signals from the device tree. This allows us
to more accurately calculate timings. see:
https://chromium-review.googlesource.com/#/c/232774/
Signed-off-by: Addy Ke <addy.ke@rock-chips.com>
Reviewed-by: Doug Anderson <dianders@chromium.org>
Tested-by: Doug Anderson <dianders@chromium.org>
[wsa: fixed a typo in the docs]
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
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git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core
Pull driver core update from Greg KH:
"Here's the set of driver core patches for 3.19-rc1.
They are dominated by the removal of the .owner field in platform
drivers. They touch a lot of files, but they are "simple" changes,
just removing a line in a structure.
Other than that, a few minor driver core and debugfs changes. There
are some ath9k patches coming in through this tree that have been
acked by the wireless maintainers as they relied on the debugfs
changes.
Everything has been in linux-next for a while"
* tag 'driver-core-3.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (324 commits)
Revert "ath: ath9k: use debugfs_create_devm_seqfile() helper for seq_file entries"
fs: debugfs: add forward declaration for struct device type
firmware class: Deletion of an unnecessary check before the function call "vunmap"
firmware loader: fix hung task warning dump
devcoredump: provide a one-way disable function
device: Add dev_<level>_once variants
ath: ath9k: use debugfs_create_devm_seqfile() helper for seq_file entries
ath: use seq_file api for ath9k debugfs files
debugfs: add helper function to create device related seq_file
drivers/base: cacheinfo: remove noisy error boot message
Revert "core: platform: add warning if driver has no owner"
drivers: base: support cpu cache information interface to userspace via sysfs
drivers: base: add cpu_device_create to support per-cpu devices
topology: replace custom attribute macros with standard DEVICE_ATTR*
cpumask: factor out show_cpumap into separate helper function
driver core: Fix unbalanced device reference in drivers_probe
driver core: fix race with userland in device_add()
sysfs/kernfs: make read requests on pre-alloc files use the buffer.
sysfs/kernfs: allow attributes to request write buffer be pre-allocated.
fs: sysfs: return EGBIG on write if offset is larger than file size
...
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The i2c input clock can change dynamically, e.g. on the RK3066 where
pclk_i2c0 and pclk_i2c1 are connected to the armclk, which changes
rate on cpu frequency scaling.
Until now, we incorrectly called clk_get_rate() while holding the
i2c->lock in rk3x_i2c_xfer() to adapt to clock rate changes.
Thanks to Huang Tao for reporting this issue.
Do it properly now using the clk notifier framework. The callback
logic was taken from i2c-cadence.c.
Also rename all misleading "i2c_rate" variables to "clk_rate", as they
describe the *input* clk rate.
Signed-off-by: Max Schwarz <max.schwarz@online.de>
Tested-by: Doug Anderson <dianders@chromium.org> on RK3288
Reviewed-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
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As show in I2C specification:
- Standard-mode: the minimum HIGH period of the scl clock is 4.0us
the minimum LOW period of the scl clock is 4.7us
- Fast-mode: the minimum HIGH period of the scl clock is 0.6us
the minimum LOW period of the scl clock is 1.3us
I have measured i2c SCL waveforms in fast-mode by oscilloscope
on rk3288-pinky board. the LOW period of the scl clock is 1.3us.
It is so critical that we must adjust LOW division to increase
the LOW period of the scl clock.
Thanks Doug for the suggestion about division formulas.
Signed-off-by: Addy Ke <addy.ke@rock-chips.com>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Doug Anderson <dianders@chromium.org>
Reviewed-by: Max Schwarz <max.schwarz@online.de>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
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A platform_driver does not need to set an owner, it will be populated by the
driver core.
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
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git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux
Pull i2c updates from Wolfram Sang:
"Highlights from the I2C subsystem for 3.18:
- new drivers for Axxia AM55xx, and Hisilicon hix5hd2 SoC.
- designware driver gained AMD support, exynos gained exynos7 support
The rest is usual driver stuff. Hopefully no lowlights this time"
* 'i2c/for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
i2c: i801: Add Device IDs for Intel Sunrise Point PCH
i2c: hix5hd2: add i2c controller driver
i2c-imx: Disable the clock on probe failure
i2c: designware: Add support for AMD I2C controller
i2c: designware: Rework probe() to get clock a bit later
i2c: designware: Default to fast mode in case of ACPI
i2c: axxia: Add I2C driver for AXM55xx
i2c: exynos: add support for HSI2C module on Exynos7
i2c: mxs: detect No Slave Ack on SELECT in PIO mode
i2c: cros_ec: Remove EC_I2C_FLAG_10BIT
i2c: cros-ec-tunnel: Add of match table
i2c: rcar: remove sign-compare flaw
i2c: ismt: Use minimum descriptor size
i2c: imx: Add arbitration lost check
i2c: rk3x: Remove unlikely() annotations
i2c: rcar: check for no IRQ in rcar_i2c_irq()
i2c: rcar: make rcar_i2c_prepare_msg() *void*
i2c: rcar: simplify check for last message
i2c: designware: add support of platform data to set I2C mode
i2c: designware: add support of I2C standard mode
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i2cdetect -q was broken (everything was a false positive, and no transfers were
actually being sent over i2c). The way it works is by sending a 0 length write
request and checking for NACK. This patch fixes the 0 length writes and actually
sends them.
Reported-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Alexandru M Stan <amstan@chromium.org>
Tested-by: Doug Anderson <dianders@chromium.org>
Tested-by: Max Schwarz <max.schwarz@online.de>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Cc: stable@kernel.org
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Having a transfer more than 32 bits is not all that unlikely. Remove
the annotation.
The unlikely in the IRQ handler can't gain us much. It's not in a
loop, so at most it would save 1 instruction per IRQ, which isn't
much. In fact on the compiler I tested it produced the exact same
code. Remove it too.
Suggested-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
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I2C_CLKDIV register descripted in the previous version of
RK3x chip manual is incorrect. Plus 1 is required.
The correct formula:
- T(SCL_HIGH) = T(PCLK) * (CLKDIVH + 1) * 8
- T(SCL_LOW) = T(PCLK) * (CLKDIVL + 1) * 8
- (SCL Divsor) = 8 * ((CLKDIVL + 1) + (CLKDIVH + 1))
- SCL = PCLK / (CLK Divsor)
It will be updated to the latest version of chip manual.
Signed-off-by: Addy Ke <addy.ke@rock-chips.com>
Reviewed-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Cc: stable@kernel.org
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In rk3x SOC, the I2C controller can receive/transmit up to 32 bytes data
in one chunk, so the size of data to be write/read to/from TXDATAx/RXDATAx
must be less than or equal 32 bytes at a time.
Tested on rk3288-pinky board, elan receive 158 bytes data.
Signed-off-by: Addy Ke <addy.ke@rock-chips.com>
Acked-by: Max Schwarz <max.schwarz@online.de>
Reviewed-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Cc: stable@kernel.org
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If slave holds scl, I2C_IPD[7] will be set 1 by controller
for debugging. Driver must ignore it.
[ 5.752391] rk3x-i2c ff160000.i2c: unexpected irq in WRITE: 0x80
[ 5.939027] rk3x-i2c ff160000.i2c: timeout, ipd: 0x80, state: 4
Signed-off-by: Addy Ke <addy.ke@rock-chips.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Cc: stable@kernel.org
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drivers/i2c/busses/i2c-rk3x.c:610:69-70: rk3x_i2c_match is not NULL terminated at line 610
Make sure of_device_id tables are NULL terminated
Generated by: /kbuild/src/linux/scripts/coccinelle/misc/of_table.cocci
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
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Driver for the native I2C adapter found in Rockchip RK3xxx SoCs.
Configuration is only possible through devicetree. The driver is
interrupt driven and supports the I2C_M_IGNORE_NAK mangling bit.
Signed-off-by: Max Schwarz <max.schwarz@online.de>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
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