Hi Paul,

On Monday 22 February 2016 12:01 PM, Paul Walmsley wrote:

Kishon,

On Mon, 22 Feb 2016, Kishon Vijay Abraham I wrote:

quoted

Sekhar,

On Thursday 18 February 2016 07:51 PM, Sekhar Nori wrote:

quoted

On Friday 12 February 2016 10:50 PM, Suman Anna wrote:

quoted

Sekhar,
Will you be following up with above suggestion since Kishon is gonna be out?

Alright, noticed this action for me :) Went through the thread, and 
looks like this is what we want to see?

Thanks,
Sekhar

---8<---
From e3ba368f2235e1bf38a22ba8ea4e5c12aaafda19 Mon Sep 17 00:00:00 2001
Message-Id: [off-list ref]
From: Sekhar Nori <redacted>
Date: Thu, 18 Feb 2016 16:49:56 +0530
Subject: [PATCH 1/1] ARM: DRA7: hwmod: Add custom reset handler for PCIeSS

Add a custom reset handler for DRA7x PCIeSS. This
handler is required to deassert PCIe hardreset lines
after they have been asserted.

This enables the PCIe driver to access registers after
PCIeSS has been runtime enabled without having to
deassert hardreset lines itself.

With this patch applied, used lspci to make sure
connected PCIe device enumerates on DRA74x and DRA72x
EVMs.

Signed-off-by: Sekhar Nori <redacted>
---
Applies to tag for-v4.6/omap-hwmod-a of Paul W's tree.

 arch/arm/mach-omap2/omap_hwmod_7xx_data.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/arch/arm/mach-omap2/omap_hwmod_7xx_data.c b/arch/arm/mach-omap2/omap_hwmod_7xx_data.c
index b61355e2a771..252b74633e31 100644
--- a/arch/arm/mach-omap2/omap_hwmod_7xx_data.c
+++ b/arch/arm/mach-omap2/omap_hwmod_7xx_data.c

@@ -1526,8 +1526,31 @@ static struct omap_hwmod dra7xx_ocp2scp3_hwmod = {
  *
  */
 
+/*
+ * As noted in documentation for _reset() in omap_hwmod.c, the stock reset
+ * functionality of OMAP HWMOD layer does not deassert the hardreset lines
+ * associated with an IP automatically leaving the driver to handle that
+ * by itself. This does not work for PCIeSS which needs the reset lines
+ * deasserted for the driver to start accessing registers.
+ *
+ * We use a PCIeSS HWMOD class specific reset handler to deassert the hardreset
+ * lines after asserting them.
+ */
+static int dra7xx_pciess_reset(struct omap_hwmod *oh)
+{
+	int i;
+
+	for (i = 0; i < oh->rst_lines_cnt; i++) {
+		omap_hwmod_assert_hardreset(oh, oh->rst_lines[i].name);
+		omap_hwmod_deassert_hardreset(oh, oh->rst_lines[i].name);
+	}
+
+	return 0;
+}
+
 static struct omap_hwmod_class dra7xx_pciess_hwmod_class = {
 	.name	= "pcie",
+	.reset	= dra7xx_pciess_reset,
 };

Thanks for the patch.

Could you please test the bind/unbind functionality just to make sure it 
works?

The pci-dra7xx driver neither expose the bind/unbind sysfs entry nor can be
built as module.

However I hacked the pci-dra7xx driver to be built as module [and reverted
Commit 5de85b9d57ab ("PM / runtime: Re-init runtime PM states at probe error
and driver unbind")] and I don't see an abort when the PCI registers are
accessed after rmmod/modprobe cycle (that was the issue that Sekhar's patch
tried to solve). However PCI as such doesn't work after rmmod/modprobe cycle
[1], but this is a different issue most likely in PCIe core and has to debugged.

In summary, there are other issues in PCI across rmmod/modprobe cycle but the
reset of pci-dra7xx happens fine with this patch.

Thanks
Kishon

[1] -> http://pastebin.ubuntu.com/15169387/