Kumar Gala wrote:
On Dec 3, 2008, at 11:04 PM, Becky Bruce wrote:
include/flash.h was commented to say that the address in flash_info->start was a physical address. However, from u-boot's point of view, and looking at most flash code, it makes more sense for this to be a virtual address. So I corrected the comment to indicate that this was a virtual address.
The only flash driver that was actually treating the address as physical was the mtd/cfi_flash driver. However, this code was using it inconsistently as it actually directly dereferenced the "start" element, while it used map_physmem to get a virtual address in other places. I changed this driver so that the code which initializes the info->start field calls map_physmem to get a virtual address, eliminating the need for further map_physmem calls. The code is now consistent.
The *only* place a physical address should be used is when defining the flash banks list that is used to initialize the flash_info struct. I have fixed the one platform that was impacted by this change (MPC8641D).
Signed-off-by: Becky Bruce beckyb@kernel.crashing.org
drivers/mtd/cfi_flash.c | 53 +++++++++++++++++ +---------------------- include/configs/MPC8641HPCN.h | 2 +- include/flash.h | 2 +- 3 files changed, 26 insertions(+), 31 deletions(-)
Stefan,
Have you reviewed this. I'm not sure if remvoing the map_physmem() is the right answer because I'm assuming Haavard added them for a reason (AVR32?). Should we instead change info->start to be a phys_addr_t?
There was definitely a reason: On AVR32, the caches are enabled by default, and I prefer that they stay that way since it makes everything faster. But when dealing with the flash, we must bypass the caches by using a different virtual address which maps to the same physical memory.
From what I can tell from a quick scan, this patch doesn't seem to change that; all it does is push the map_physmem() call a bit up the stack so it gets called less often. That seems like a good thing to me.
However, what I don't understand is if the 'start' array is really supposed to hold virtual addresses, why isn't it an array of pointers?
Haavard