Santosh Shilimkar <santosh.shilimkar@xxxxxx> writes: > On Thursday 08 August 2013 04:05 PM, Kevin Hilman wrote: >> Santosh Shilimkar <santosh.shilimkar@xxxxxx> writes: >> >>> On Thursday 08 August 2013 02:16 PM, Kevin Hilman wrote: >>>> Dave Gerlach <d-gerlach@xxxxxx> writes: >>>> >>>>> From: Vaibhav Bedia <vaibhav.bedia@xxxxxx> >>>>> >>>>> SDRAM controller on AM33XX requires that a modification of certain >>>>> bit-fields in PWR_MGMT_CTRL register (ref. section 7.3.5.13 in >>>>> AM335x-Rev H) is followed by a dummy read access to SDRAM. This >>>>> scenario arises when entering a low power state like DeepSleep. >>>>> To ensure that the read is not from a cached region we reserve >>>>> some memory during bootup using the arm_memblock_steal() API. >>>> >>>> Hmm, sounds to me an awful lot like the existing omap_bus_sync() ? >>>> >>> All the credit of that awful omap_bus_sync() goes to me since >>> I introduced it. And I keep beating the hardware guys >>> who have not left a choice but to introduce the ugly work >>> around in software. ;-) >> >> Agreed, but what's even more awful than the current version is >> duplicating it in a slightly different way using yet another whole page >> mapping for a single read/write location. >> > The real issue is limitation of the kernel memory steal(memblock) API which > won't let you still less than 1 MB. It would have been ok for page allocation > because that is any way what you will get minimum on standard non-cached > allocations. All the more reason that the omap_bus_sync() should be refactored slightly in a way that would be reusable for AM33xx. Kevin -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
