LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
To: Kishon Vijay Abraham I <kishon@ti.com>
Cc: Arnd Bergmann <arnd@arndb.de>, Rob Herring <robh@kernel.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Lokesh Vutla <lokeshvutla@ti.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Tom Joseph <tjoseph@cadence.com>,
	linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	nadeem@cadence.com
Subject: Re: [PATCH v2 5/6] misc: pci_endpoint_test: Do not request or allocate IRQs in probe
Date: Thu, 5 Aug 2021 12:26:39 +0100	[thread overview]
Message-ID: <20210805112639.GA20438@lpieralisi> (raw)
In-Reply-To: <02c1ddb7-539e-20a0-1bef-e10e76922a0e@ti.com>

On Wed, Aug 04, 2021 at 07:32:44PM +0530, Kishon Vijay Abraham I wrote:
> Hi Lorenzo,
> 
> On 03/08/21 3:28 pm, Lorenzo Pieralisi wrote:
> > On Tue, Aug 03, 2021 at 01:19:31PM +0530, Kishon Vijay Abraham I wrote:
> >> Allocation of IRQ vectors and requesting IRQ is done as part of
> >> PCITEST_SET_IRQTYPE. Do not request or allocate IRQs in probe for
> >> AM654 and J721E so that the user space test script has better control
> >> of the devices for which the IRQs are configured. Since certain user
> >> space scripts could rely on allocation of IRQ vectors during probe,
> >> remove allocation of IRQs only for TI's K3 platform.
> >>
> >> Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
> >> ---
> >>  drivers/misc/pci_endpoint_test.c | 19 +++++++++++++------
> >>  1 file changed, 13 insertions(+), 6 deletions(-)
> > 
> > I don't claim to understand the inner details of the endpoint test
> > device but it looks like this approach should be redesigned.
> > 
> > I don't believe using devices quirks is the best approach to
> > expose/remove a feature to userspace, this can soon become
> > unmaintenable.
> > 
> > Maybe you can elaborate a bit more on what the real issue is please ?
> 
> The actual reason for introducing this patch (affects only AM654 and
> J721E) is due to Errata ID #i2101 GIC: ITS Misbehavior
> (https://www.ti.com/lit/er/sprz455a/sprz455a.pdf). So if more than 5
> devices use GIC ITS simultaneously, GIC fails to raise interrupts.
> 
> Though this patch is not an actual workaround for the issue (the
> workaround is in GIC ITS driver provided in the errata document), it
> helps to keep testing PCIe RC/EP using pci-endpoint-test even when
> multiple pci-epf-test endpoint devices are connected (Normal test-setup
> having J721E-J721E back to back connection can support 21 pci-epf-test
> devices). So this patch lets user to individually enable interrupts for
> each of the devices and could disable after the interrupt test.
> 
> Since pci_endpoint_test is used only for testing PCIE RC/EP
> communication and pci-endpoint-test has already implemented
> PCITEST_SET_IRQTYPE for the userspace to enable interrupt, tried to not
> enable the interrupts of all the devices by default in the probe (for
> AM654 and J721E where this errata applies).

I understand - what I am asking is:

is it possible, instead of applying this patch, to make

pci_endpoint_test_alloc_irq_vectors() and pci_endpoint_test_request_irq()

fail in the target platforms instead of preventing to call them ?

My worry is that you may end up with more corner cases in the future
and peppering code with is_() calls to work around them which does
not look right.

Thanks,
Lorenzo

> Thanks,
> Kishon
> 
> > 
> > Thanks,
> > Lorenzo
> > 
> >> diff --git a/drivers/misc/pci_endpoint_test.c b/drivers/misc/pci_endpoint_test.c
> >> index c7ee34013485..9740f2a0e7cd 100644
> >> --- a/drivers/misc/pci_endpoint_test.c
> >> +++ b/drivers/misc/pci_endpoint_test.c
> >> @@ -79,6 +79,9 @@
> >>  #define PCI_DEVICE_ID_RENESAS_R8A774C0		0x002d
> >>  #define PCI_DEVICE_ID_RENESAS_R8A774E1		0x0025
> >>  
> >> +#define is_j721e_pci_dev(pdev)         \
> >> +		((pdev)->device == PCI_DEVICE_ID_TI_J721E)
> >> +
> >>  static DEFINE_IDA(pci_endpoint_test_ida);
> >>  
> >>  #define to_endpoint_test(priv) container_of((priv), struct pci_endpoint_test, \
> >> @@ -810,9 +813,11 @@ static int pci_endpoint_test_probe(struct pci_dev *pdev,
> >>  
> >>  	pci_set_master(pdev);
> >>  
> >> -	if (!pci_endpoint_test_alloc_irq_vectors(test, irq_type)) {
> >> -		err = -EINVAL;
> >> -		goto err_disable_irq;
> >> +	if (!(is_am654_pci_dev(pdev) || is_j721e_pci_dev(pdev))) {
> >> +		if (!pci_endpoint_test_alloc_irq_vectors(test, irq_type)) {
> >> +			err = -EINVAL;
> >> +			goto err_disable_irq;
> >> +		}
> >>  	}
> >>  
> >>  	for (bar = 0; bar < PCI_STD_NUM_BARS; bar++) {
> >> @@ -850,9 +855,11 @@ static int pci_endpoint_test_probe(struct pci_dev *pdev,
> >>  		goto err_ida_remove;
> >>  	}
> >>  
> >> -	if (!pci_endpoint_test_request_irq(test)) {
> >> -		err = -EINVAL;
> >> -		goto err_kfree_test_name;
> >> +	if (!(is_am654_pci_dev(pdev) || is_j721e_pci_dev(pdev))) {
> >> +		if (!pci_endpoint_test_request_irq(test)) {
> >> +			err = -EINVAL;
> >> +			goto err_kfree_test_name;
> >> +		}
> >>  	}
> >>  
> >>  	misc_device = &test->miscdev;
> >> -- 
> >> 2.17.1
> >>

  reply	other threads:[~2021-08-05 11:26 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-03  7:49 [PATCH v2 0/6] PCI: Add support for J7200 and AM64 Kishon Vijay Abraham I
2021-08-03  7:49 ` [PATCH v2 1/6] PCI: cadence: Use bitfield for *quirk_retrain_flag* instead of bool Kishon Vijay Abraham I
2021-08-03  7:49 ` [PATCH v2 2/6] PCI: cadence: Add quirk flag to set minimum delay in LTSSM Detect.Quiet state Kishon Vijay Abraham I
2021-08-03 10:08   ` Lorenzo Pieralisi
2021-08-03  7:49 ` [PATCH v2 3/6] PCI: j721e: Add PCIe support for J7200 Kishon Vijay Abraham I
2021-08-03 10:14   ` Lorenzo Pieralisi
2021-08-03  7:49 ` [PATCH v2 4/6] PCI: j721e: Add PCIe support for AM64 Kishon Vijay Abraham I
2021-08-03  7:49 ` [PATCH v2 5/6] misc: pci_endpoint_test: Do not request or allocate IRQs in probe Kishon Vijay Abraham I
2021-08-03  9:58   ` Lorenzo Pieralisi
2021-08-04 14:02     ` Kishon Vijay Abraham I
2021-08-05 11:26       ` Lorenzo Pieralisi [this message]
2021-08-09  4:36         ` Kishon Vijay Abraham I
2021-08-03  7:49 ` [PATCH v2 6/6] misc: pci_endpoint_test: Add deviceID for AM64 and J7200 Kishon Vijay Abraham I
2021-08-03 10:52 ` [PATCH v2 0/6] PCI: Add support for J7200 and AM64 Lorenzo Pieralisi
2021-08-11 12:26   ` Kishon Vijay Abraham I

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210805112639.GA20438@lpieralisi \
    --to=lorenzo.pieralisi@arm.com \
    --cc=arnd@arndb.de \
    --cc=bhelgaas@google.com \
    --cc=gregkh@linuxfoundation.org \
    --cc=kishon@ti.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-omap@vger.kernel.org \
    --cc=linux-pci@vger.kernel.org \
    --cc=lokeshvutla@ti.com \
    --cc=nadeem@cadence.com \
    --cc=robh@kernel.org \
    --cc=tjoseph@cadence.com \
    --subject='Re: [PATCH v2 5/6] misc: pci_endpoint_test: Do not request or allocate IRQs in probe' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).