linux-kernel - Re: [PATCH v2 5/6] misc: pci_endpoint_test: Do not request or allocate IRQs in probe

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Message-ID: <20210803095839.GA11252@lpieralisi>
Date:   Tue, 3 Aug 2021 10:58:39 +0100
From:   Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:     Kishon Vijay Abraham I <kishon@...com>
Cc:     Arnd Bergmann <arnd@...db.de>, Rob Herring <robh@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Lokesh Vutla <lokeshvutla@...com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Tom Joseph <tjoseph@...ence.com>, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, nadeem@...ence.com
Subject: Re: [PATCH v2 5/6] misc: pci_endpoint_test: Do not request or
 allocate IRQs in probe

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@...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 ?

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
>