From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3rypln6yQHzDqQM for ; Tue, 26 Jul 2016 03:53:57 +1000 (AEST) Received: from pps.filterd (m0098416.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.11/8.16.0.11) with SMTP id u6PHhLC0143234 for ; Mon, 25 Jul 2016 13:53:55 -0400 Received: from e35.co.us.ibm.com (e35.co.us.ibm.com [32.97.110.153]) by mx0b-001b2d01.pphosted.com with ESMTP id 24dnc553ef-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Mon, 25 Jul 2016 13:53:54 -0400 Received: from localhost by e35.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 25 Jul 2016 11:53:54 -0600 Subject: Re: [PATCH] powernv/pci: Add PHB register dump debugfs handle To: Gavin Shan , Russell Currey References: <20160722052336.3340-1-ruscur@russell.cc> <20160722063655.GA28438@gwshan> Cc: linuxppc-dev@lists.ozlabs.org From: Tyrel Datwyler Date: Mon, 25 Jul 2016 10:53:49 -0700 MIME-Version: 1.0 In-Reply-To: <20160722063655.GA28438@gwshan> Content-Type: text/plain; charset=utf-8 Message-Id: <5796522D.9040601@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 07/21/2016 11:36 PM, Gavin Shan wrote: > On Fri, Jul 22, 2016 at 03:23:36PM +1000, Russell Currey wrote: >> On EEH events the kernel will print a dump of relevant registers. >> If EEH is unavailable (i.e. CONFIG_EEH is disabled, a new platform >> doesn't have EEH support, etc) this information isn't readily available. >> >> Add a new debugfs handler to trigger a PHB register dump, so that this >> information can be made available on demand. >> >> Signed-off-by: Russell Currey > > Reviewed-by: Gavin Shan > >> --- >> arch/powerpc/platforms/powernv/pci-ioda.c | 35 +++++++++++++++++++++++++++++++ >> 1 file changed, 35 insertions(+) >> >> diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c >> index 891fc4a..ada2f3c 100644 >> --- a/arch/powerpc/platforms/powernv/pci-ioda.c >> +++ b/arch/powerpc/platforms/powernv/pci-ioda.c >> @@ -3018,6 +3018,38 @@ static void pnv_ioda_setup_pe_seg(struct pnv_ioda_pe *pe) >> } >> } >> >> +#ifdef CONFIG_DEBUG_FS >> +static ssize_t pnv_pci_debug_write(struct file *filp, >> + const char __user *user_buf, >> + size_t count, loff_t *ppos) >> +{ >> + struct pci_controller *hose = filp->private_data; >> + struct pnv_phb *phb; >> + int ret = 0; > > Needn't initialize @ret in advance. The code might be simpler, but it's > only a personal preference: I believe its actually preferred that it not be initialized in advance so that the tooling can warn you about conditional code paths where you may have forgotten to set a value. Or as Gavin suggests to explicitly use error values in the return statements. -Tyrel > > struct pci_controller *hose = filp->private_data; > struct pnv_phb *phb = hose ? hose->private_data : NULL; > > if (!phb) > return -ENODEV; > >> + >> + if (!hose) >> + return -EFAULT; >> + >> + phb = hose->private_data; >> + if (!phb) >> + return -EFAULT; >> + >> + ret = opal_pci_get_phb_diag_data2(phb->opal_id, phb->diag.blob, >> + PNV_PCI_DIAG_BUF_SIZE); >> + >> + if (!ret) >> + pnv_pci_dump_phb_diag_data(phb->hose, phb->diag.blob); >> + >> + return ret < 0 ? ret : count; > > return ret == OPAL_SUCCESS ? count : -EIO; > >> +} >> + >> +static const struct file_operations pnv_pci_debug_ops = { >> + .open = simple_open, >> + .llseek = no_llseek, >> + .write = pnv_pci_debug_write, > > It might be reasonable to dump the diag-data on read if it is trying > to do it on write. > >> +}; >> +#endif /* CONFIG_DEBUG_FS */ >> + >> static void pnv_pci_ioda_create_dbgfs(void) >> { >> #ifdef CONFIG_DEBUG_FS >> @@ -3036,6 +3068,9 @@ static void pnv_pci_ioda_create_dbgfs(void) >> if (!phb->dbgfs) >> pr_warning("%s: Error on creating debugfs on PHB#%x\n", >> __func__, hose->global_number); >> + >> + debugfs_create_file("regdump", 0200, phb->dbgfs, hose, >> + &pnv_pci_debug_ops); > > "diag-data" might be indicating or a better one you can name :) > > Thanks, > Gavin > >> } >> #endif /* CONFIG_DEBUG_FS */ >> } >> -- >> 2.9.0 >> > > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev >