From: Paul Walmsley <paul@pwsan.com>
To: Suman Anna <s-anna@ti.com>
Cc: Kishon Vijay Abraham I <kishon@ti.com>,
Tony Lindgren <tony@atomide.com>,
Bjorn Helgaas <bhelgaas@google.com>,
richardcochran@gmail.com, Russell King <linux@arm.linux.org.uk>,
linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, nsekhar@ti.com
Subject: Re: [PATCH v3 3/3] pci: dra7xx: use pdata callbacks to perform reset
Date: Tue, 9 Feb 2016 19:36:40 +0000 (UTC) [thread overview]
Message-ID: <alpine.DEB.2.02.1602091932160.2906@utopia.booyaka.com> (raw)
In-Reply-To: <56BA2495.9020407@ti.com>
Hi Suman
On Tue, 9 Feb 2016, Suman Anna wrote:
> On 02/09/2016 02:49 AM, Paul Walmsley wrote:
> > On Mon, 8 Feb 2016, Suman Anna wrote:
> >> On 02/07/2016 08:48 PM, Paul Walmsley wrote:
> >>> On Tue, 2 Feb 2016, Kishon Vijay Abraham I wrote:
> >>>
> >>>> Paul, what do you think is the best way forward to perform reset?
> >>>
> >>> Many of the IP blocks with PRM hardreset lines are processor IP blocks.
> >>> Those often need special reset handling to ensure that WFI/HLT-like
> >>> instructions are executed after reset. This special handling ensures that
> >>> the IP blocks' bus initiator interfaces indicate that they are in standby
> >>> to the PRCM - thus allowing power management for the rest of the chip to
> >>> work correctly.
> >>>
> >>> But that doesn't seem to be the case with PCIe - and maybe others -
> >>> possibly some of the MMUs?
> >>
> >> Yeah, the sequencing between clocks and resets would still be the same
> >> for MMUs, so, adding the custom flags for MMUs is fine.
> >
> > I'm curious as to whether HWMOD_CUSTOM_HARDRESET is needed for the MMUs.
> > We've stated that the main point of the custom hardreset code is to handle
> > processors that need to be placed into WFI/HLT, but it doesn't seem like
> > there would be an equivalent for MMUs. Thoughts?
>
> The current OMAP IOMMU code already leverages the pdata ops for
> performing the resets, so not adding the flags would also require
> additional changes in the driver.
>
> Also, the reset lines controlling the MMUs actually also manage the
> reset for all the other sub-modules other than the processor cores
> within the sub-systems. We have currently different issues (see [1] for
> eg. around the IPU sub-system entering RET in between), so from a PM
> point of view, we do prefer to place the MMUs also in reset when we are
> runtime suspended.
Should we reassert hardreset in _idle() for IP blocks that don't have
HWMOD_CUSTOM_HARDRESET set on them? Would that allow us to use this
mechanism for the uncore hardreset lines, or are there other quirks?
Also - would that address the potential issue that you mentioned with the
PCIe block, or is that a different issue?
- Paul
next prev parent reply other threads:[~2016-02-09 19:36 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-14 14:11 [PATCH v3 0/3] dra7xx: get pcie working in mainline Kishon Vijay Abraham I
2016-01-14 14:11 ` [PATCH v3 1/3] ARM: DRA7: hwmod: Add reset data for PCIe Kishon Vijay Abraham I
2016-02-08 1:50 ` Paul Walmsley
2016-01-14 14:11 ` [PATCH v3 2/3] ARM: DRA7: add pdata-quirks to do reset of PCIe Kishon Vijay Abraham I
2016-01-15 19:19 ` Suman Anna
2016-01-15 19:22 ` Tony Lindgren
2016-01-15 19:41 ` Suman Anna
2016-01-18 9:12 ` Sekhar Nori
2016-01-27 17:23 ` Tony Lindgren
2016-01-14 14:11 ` [PATCH v3 3/3] pci: dra7xx: use pdata callbacks to perform reset Kishon Vijay Abraham I
2016-01-27 17:31 ` Tony Lindgren
2016-01-27 18:16 ` Suman Anna
2016-01-27 18:56 ` Tony Lindgren
2016-01-27 23:16 ` Suman Anna
2016-01-28 18:31 ` Tony Lindgren
2016-01-28 21:15 ` Suman Anna
2016-02-02 10:40 ` Kishon Vijay Abraham I
2016-02-05 4:19 ` Kishon Vijay Abraham I
2016-02-08 2:48 ` Paul Walmsley
2016-02-08 20:56 ` Suman Anna
2016-02-09 8:49 ` Paul Walmsley
2016-02-09 17:40 ` Suman Anna
2016-02-09 19:36 ` Paul Walmsley [this message]
2016-02-10 1:42 ` Suman Anna
2016-02-10 5:38 ` Kishon Vijay Abraham I
2016-02-11 19:27 ` Paul Walmsley
2016-02-11 22:04 ` Suman Anna
2016-02-12 6:49 ` Kishon Vijay Abraham I
2016-02-12 17:20 ` Suman Anna
2016-02-18 14:21 ` Sekhar Nori
2016-02-18 17:23 ` Paul Walmsley
2016-02-18 18:27 ` Suman Anna
2016-02-22 6:18 ` Kishon Vijay Abraham I
2016-02-22 6:31 ` Paul Walmsley
2016-02-22 9:55 ` Kishon Vijay Abraham I
2016-02-23 11:57 ` Kishon Vijay Abraham I
2016-02-23 18:28 ` Paul Walmsley
2016-02-24 6:21 ` Kishon Vijay Abraham I
2016-03-01 8:25 ` Paul Walmsley
2016-03-01 11:55 ` Kishon Vijay Abraham I
2016-03-01 14:43 ` Bjorn Helgaas
2016-03-01 16:55 ` Suman Anna
2016-02-11 20:43 ` Suman Anna
2016-02-12 6:55 ` Kishon Vijay Abraham I
2016-02-10 5:36 ` Kishon Vijay Abraham I
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