[lkml]   [2016]   [Jul]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH] Exchange the Assignments of `MEMORYs' and `CFGs/IOs' in Designware PCIe Driver
On 2016/7/3 23:27, Pratyush Anand wrote:
> On Tue, Jun 28, 2016 at 1:42 PM, dongbo (E) <> wrote:
>> From: Dong Bo <>
>> In designware PCIe driver, the iatu0 is used for both CFG and IO accesses.
>> When sending CFGs to peripherals (e.g. lspci), iatu0 frequently switches
>> between CFG and IO alternatively.
>> A MEMORY probably be sent as an IOs by mistake. Considering the following
>> configurations:
>> MEMORY -> BASE_ADDR: 0xb4100000, LIMIT: 0xb4100FFF, TYPE=mem
>> CFG -> BASE_ADDR: 0xb4000000, LIMIT: 0xb4000FFF, TYPE=cfg
>> Suppose PCIe has just completed a CFG access, to switch back to IO, it set
>> the BASE_ADDR to 0xFFFFFFFF, LIMIT 0xFFFFFFFE and TYPE to io. When another
>> CFG comes, the BASE_ADDR is set to 0xb4000000 to switch to CFG. At this
>> moment, a MEMORY access shows up, since it matches with iatu0
>> (due to 0xb4000000 <= MEMORY BASE_ADDR <= MEMORY LIMIE <= 0xFFFFFFF), it
>> is treated as an IO access by mistake, then sent to perpheral.
>> This patch fixes the problem by exchanging the assignments of `MEMORYs'
>> and `CFGs/IOs', which assigning MEMEORYs to iatu0, CFGs and IOs to iatu1.
> Had a re-thought on it. While it will fix wrong memory access in your
> case, it can still cause issues with IO access for some other
> platform.
> Can you please test [1] and check it that works for you. You will need
> to define num-viewport in your device tree file.
> ~Pratyush
> [1]
> .

Checked, it works for us.

I think it would be better to exchange the assignments of MEMORYs and
CFGs/IOs when num_viewports <= 2, cause it fixes wrong memory access.

As you mentioned, other corner point for failure is still there while
there are only two viewports. It seems that there is not a perfect

Best Regards
Dong Bo

 \ /
  Last update: 2016-07-04 10:21    [W:0.042 / U:28.536 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site