Re: [PATCH v3 3/3] pci: dra7xx: use pdata callbacks to perform reset

From: Tony Lindgren
Date: Wed Jan 27 2016 - 13:56:57 EST

* Suman Anna <s-anna@xxxxxx> [160127 10:17]:
> On 01/27/2016 11:31 AM, Tony Lindgren wrote:
> > Why do you need another reset here? Can't you just implement PM runtime
> > in the driver and do the usual pm_runtime_put_sync followed by
> > pm_runtime_disable?
> The omap_hwmod_enable/disable code does not deal with hardresets (PRCM
> reset lines) and so the pm_runtime_get_sync/put_sync only end up dealing
> with clocks, and we need to invoke the reset functions separately.
> Modules with softresets in SYSCONFIG are ok, as they are dealt with
> properly.

Hmm _reset() in omap_hwmod.c has this to call _assert_hardreset:

if (oh->class->reset) {
r = oh->class->reset(oh);
} else {
if (oh->rst_lines_cnt > 0) {
for (i = 0; i < oh->rst_lines_cnt; i++)
_assert_hardreset(oh, oh->rst_lines[i].name);
return 0;
} else {
r = _ocp_softreset(oh);
if (r == -ENOENT)
r = 0;

Care to explain what exactly the problem with the hwmod code not doing
the reset on init?

And why do you need to do another reset in dra7xx_pcie_remove()?

> > Basically I'm wondering how come we need these platform data callbacks
> > at all.
> The hardresets are controlled through the
> omap_device_assert(deassert)_hardreset functions, and since these are
> limited to mach-omap2, we are invoking them through platform data callbacks.

Right.. But I'm wondering about the why you need to do this in the
driver at all part :)