lkml.org 
[lkml]   [2017]   [Oct]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 1/2] PCI: dwc: dra7xx: Create functional dependency between PCIe and PHY
From
Date
Roger,

On Tuesday 10 October 2017 12:49 PM, Roger Quadros wrote:
> On 09/10/17 12:03, Kishon Vijay Abraham I wrote:
>> PCI core access configuration space registers in resume_noirq callbacks.
>> In the case of dra7xx, PIPE3 PHY connected to PCIe controller has to be
>> enabled before accessing configuration space registers. Since
>> PIPE3 PHY is enabled by only configuring control module registers, no
>> aborts has been observed so far (though during noirq stage, interface
>> clock of PIPE3 PHY is not enabled).
>>
>> With new TRM updates, PIPE3 PHY has to be initialized (PIPE3 PHY
>> registers has to be accessed) as well which requires the interface
>> clock of PIPE3 PHY to be enabled. The interface clock of PIPE3 PHY is
>> derived from OCP2SCP and hence PCIe PHY is modeled as a child of
>> OCP2SCP. Since pm_runtime is not enabled during noirq stage,
>> pm_runtime_get_sync done in phy_init doesn't enable
>> OCP2SCP clocks resulting in abort when PIPE3 PHY registers are
>> accessed.
>
> This could be the case not only with PCIe but even with USB and SATA?

right, if USB/SATA driver has no_irq callbacks then the same issue might occur.
But looks like none of them uses no_irq callbacks.
> Maybe today it doesn't complain because USB/SATA is being resumed (by chance) after PHY?

But once pm_runtime is enabled, USB/SATA can enable PHY which in turn will
enable OCP2SCP and PHY can be accessed without any issues.

Thanks
Kishon

\
 
 \ /
  Last update: 2017-10-10 09:43    [W:0.103 / U:1.848 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site