On Fri, May 09, 2014 at 05:50:00PM +0530, Naveen Krishna Ch wrote: > On 24 April 2014 21:55, Mark Brown <broonie@xxxxxxxxxx> wrote: > >> Such solution has been proposed by Mark Brown to fix the problem of > >> the regulators not beeing available on the peripheral device probe(): > >> http://lists.infradead.org/pipermail/linux-arm-kernel/2010-March/011971.html > > 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. These drivers are buggy, if they geniunely expect and handle a missing supply then they should be using regulator_get_optional() to request the regulator and even if they don't the use of subsys_initcall() is not going to fix anything here - if a dummy regulator is going to be returned the time things are probed won't make a difference. > I2C, I2C_TUNNEL, SPI and DMA drivers are required as subsys_initcall() > for similar reason. What makes you say this? Typically those drivers don't use regulators at all.
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