[PATCH] i2c: exynos5: Initialise Samsung High Speed I2C controller early
Naveen Krishna Ch
naveenkrishna.ch at gmail.com
Fri May 9 05:20:00 PDT 2014
On 24 April 2014 21:55, Mark Brown <broonie at kernel.org> wrote:
> On Thu, Apr 24, 2014 at 08:18:36PM +0530, Naveen Krishna Chatradhi wrote:
>> This patch moves initialization code to subsys_initcall() to ensure
>> that the i2c bus is available early so the regulators can be quickly
>> probed and available for other devices on their probe() call.
>> Such solution has been proposed by Mark Brown to fix the problem of
>> the regulators not beeing available on the peripheral device probe():
> What specifically is this needed for? We *should* be able to use
> deferred probe for most things, but I know that not all subsystems are
> able to yet.
DRM related drivers like DP, FIMD, HDMI, Mixer wants to be probed ASAP
during the boot.
The real problem comes when, one of these drivers do a regulator_get().
If the physical supply is not enabled/hookedup the regulator_get() call
assumes that physical supply is present and returns a
"dummy_regulator" (But, not an error).
Because of which, Display and several other devices fails to work.
I2C, I2C_TUNNEL, SPI and DMA drivers are required as subsys_initcall()
for similar reason.
(: Nav :)
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