[EXTERNAL] Re: [PATCH v2 3/6] powerpc/eeh: Improve debug messages around device addition

Tue Jul 16 17:00:44 AEST 2019

On Tue, 2019-07-16 at 16:48 +1000, Sam Bobroff wrote:
> On Thu, Jun 20, 2019 at 01:45:24PM +1000, Oliver O'Halloran wrote:
> > On Thu, Jun 20, 2019 at 12:40 PM Alexey Kardashevskiy <aik at ozlabs.ru> wrote:
> > > On 19/06/2019 14:27, Sam Bobroff wrote:
> > > > On Tue, Jun 11, 2019 at 03:47:58PM +1000, Alexey Kardashevskiy wrote:
> > > > > On 07/05/2019 14:30, Sam Bobroff wrote:
> > > > > > Also remove useless comment.
> > > > > > 
> > > > > > Signed-off-by: Sam Bobroff <sbobroff at linux.ibm.com>
> > > > > > Reviewed-by: Alexey Kardashevskiy <aik at ozlabs.ru>
> > > > > > ---
> > > *snip*
> > > > I can see that edev will be non-NULL here, but that pr_debug() pattern
> > > > (using the PDN information to form the PCI address) is quite common
> > > > across the EEH code, so I think rather than changing a couple of
> > > > specific cases, I should do a separate cleanup patch and introduce
> > > > something like pdn_debug(pdn, "...."). What do you think?
> > > 
> > > I'd switch them all to already existing dev_dbg/pci_debug rather than
> > > adding pdn_debug as imho it should not have been used in the first place
> > > really...
> > > 
> > > > (I don't know exactly when edev->pdev can be NULL.)
> > > 
> > > ... and if you switch to dev_dbg/pci_debug, I think quite soon you'll
> > > know if it can or cannot be NULL :)
> > 
> > As far as I can tell edev->pdev is NULL in two cases:
> > 
> > 1. Before eeh_device_add_late() has been called on the pdev. The late
> > part of the add maps the pdev to an edev and sets the pdev's edev
> > pointer and vis a vis.
> > 2. While recoverying EEH unaware devices. Unaware devices are
> > destroyed and rescanned and the edev->pdev pointer is cleared by
> > pcibios_device_release()
> > 
> > In most of these cases it should be safe to use the pci_*() functions
> > rather than making a new one up for printing pdns. In the cases where
> > we might not have a PCI dev i'd make a new set of prints that take an
> > EEH dev rather than a pci_dn since i'd like pci_dn to die sooner
> > rather than later.
> > 
> > Oliver
> 
> I'll change the calls in {pnv,pseries}_pcibios_bus_add_device() and
> eeh_add_device_late() to use dev_dbg() and post a new version.
> 
> For {pnv,pseries}_eeh_probe() I'm not sure what we can do; there's no
> pci_dev available yet and while it would be nice to use the eeh_dev
> rather than the pdn, it doesn't seem to have the bus/device/fn
> information we need. Am I missing something there?  (The code in the
> probe functions seems to get it from the pci_dn.)

We do have a pci_dev in the powernv case since pnv_eeh_probe() isn't
called until the late probe happens (which is after the pci_dev has
been created). I've got some patches to rework the probe path to make
this a bit clearer, but they need a bit more work.

> 
> If there isn't an easy way around this, would it therefore be reasonable
> to just leave them open-coded as they are?

I've had this patch floating around a while that should do the trick.
The PCI_BUSNO macro is probably unnecessary since I'm sure there is
something that does it in generic code, but I couldn't find it.


>From 61ff8c23c4d13ff640fb2d069dcedacdf2ee22dd Mon Sep 17 00:00:00 2001
From: Oliver O'Halloran <oohall at gmail.com>
Date: Thu, 18 Apr 2019 18:25:13 +1000
Subject: [PATCH] powerpc/eeh: Add bdfn field to eeh_dev

Preperation for removing pci_dn from the powernv EEH code. The only thing we
really use pci_dn for is to get the bdfn of the device for config space
accesses, so adding that information to eeh_dev reduces the need to carry
around the pci_dn.

Signed-off-by: Oliver O'Halloran <oohall at gmail.com>
---
 arch/powerpc/include/asm/eeh.h     | 2 ++
 arch/powerpc/include/asm/ppc-pci.h | 2 ++
 arch/powerpc/kernel/eeh_dev.c      | 2 ++
 3 files changed, 6 insertions(+)

diff --git a/arch/powerpc/include/asm/eeh.h b/arch/powerpc/include/asm/eeh.h
index 7fd476d..a208e02 100644
--- a/arch/powerpc/include/asm/eeh.h
+++ b/arch/powerpc/include/asm/eeh.h
@@ -131,6 +131,8 @@ static inline bool eeh_pe_passed(struct eeh_pe *pe)
 struct eeh_dev {
 	int mode;			/* EEH mode			*/
 	int class_code;			/* Class code of the device	*/
+	int bdfn; 			/* bdfn of device (for cfg ops) */
+	struct pci_controller *controller;
 	int pe_config_addr;		/* PE config address		*/
 	u32 config_space[16];		/* Saved PCI config space	*/
 	int pcix_cap;			/* Saved PCIx capability	*/
diff --git a/arch/powerpc/include/asm/ppc-pci.h b/arch/powerpc/include/asm/ppc-pci.h
index cec2d64..72860de 100644
--- a/arch/powerpc/include/asm/ppc-pci.h
+++ b/arch/powerpc/include/asm/ppc-pci.h
@@ -74,6 +74,8 @@ static inline const char *eeh_driver_name(struct pci_dev *pdev)
 
 #endif /* CONFIG_EEH */
 
+#define PCI_BUSNO(bdfn) ((bdfn >> 8) & 0xff)
+
 #else /* CONFIG_PCI */
 static inline void init_pci_config_tokens(void) { }
 #endif /* !CONFIG_PCI */
diff --git a/arch/powerpc/kernel/eeh_dev.c b/arch/powerpc/kernel/eeh_dev.c
index c4317c4..7370185 100644
--- a/arch/powerpc/kernel/eeh_dev.c
+++ b/arch/powerpc/kernel/eeh_dev.c
@@ -47,6 +47,8 @@ struct eeh_dev *eeh_dev_init(struct pci_dn *pdn)
 	/* Associate EEH device with OF node */
 	pdn->edev = edev;
 	edev->pdn = pdn;
+	edev->bdfn = (pdn->busno << 8) | pdn->devfn;
+	edev->controller = pdn->phb;
 
 	return edev;
 }
-- 
2.9.5

