Hello Mark, On 24 April 2014 21:55, Mark Brown <broonie@xxxxxxxxxx> 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(): >> 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. I2C, I2C_TUNNEL, SPI and DMA drivers are required as subsys_initcall() for similar reason. -- Shine bright, (: Nav :) -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
