Re: [PATCH 10/10] misc: pci_endpoint_test: Add driver data for FSD PCIe controllers

From: Niklas Cassel <cassel@kernel.org>
To: Shradha Todi <shradha.t@samsung.com>
Cc: linux-pci@vger.kernel.org, devicetree@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-samsung-soc@vger.kernel.or, linux-kernel@vger.kernel.org,
	linux-phy@lists.infradead.org, manivannan.sadhasivam@linaro.org,
	lpieralisi@kernel.org, kw@linux.com, robh@kernel.org,
	bhelgaas@google.com, jingoohan1@gmail.com, krzk+dt@kernel.org,
	conor+dt@kernel.org, alim.akhtar@samsung.com, vkoul@kernel.org,
	kishon@kernel.org, arnd@arndb.de, m.szyprowski@samsung.com,
	jh80.chung@samsung.com
Subject: Re: [PATCH 10/10] misc: pci_endpoint_test: Add driver data for FSD PCIe controllers
Date: Mon, 19 May 2025 11:59:47 +0200	[thread overview]
Message-ID: <aCsBE7uwU9wyZIXn@ryzen> (raw)
In-Reply-To: <20250518193152.63476-11-shradha.t@samsung.com>

Hello Shradha,

On Mon, May 19, 2025 at 01:01:52AM +0530, Shradha Todi wrote:
> dma_map_single() might not return a 4KB aligned address, so add the
> default_data as driver data for FSD PCIe controllers to make it
> 4KB aligned.
> 
> Signed-off-by: Shradha Todi <shradha.t@samsung.com>
> ---
>  drivers/misc/pci_endpoint_test.c | 3 +++
>  include/linux/pci_ids.h          | 2 ++
>  2 files changed, 5 insertions(+)
> 
> diff --git a/drivers/misc/pci_endpoint_test.c b/drivers/misc/pci_endpoint_test.c
> index c4e5e2c977be..d94a94231ee5 100644
> --- a/drivers/misc/pci_endpoint_test.c
> +++ b/drivers/misc/pci_endpoint_test.c
> @@ -1110,6 +1110,9 @@ static const struct pci_device_id pci_endpoint_test_tbl[] = {
>  	{ PCI_DEVICE(PCI_VENDOR_ID_FREESCALE, PCI_DEVICE_ID_LS1088A),
>  	  .driver_data = (kernel_ulong_t)&default_data,
>  	},
> +	{ PCI_DEVICE(PCI_VENDOR_ID_TESLA, 0x7777),
> +	  .driver_data = (kernel_ulong_t)&default_data,
> +	},

Are you sure that you actually require this?

Since we now have these two commits:
e73ea1c2d4d8 ("PCI: dwc: endpoint: Implement the pci_epc_ops::align_addr() operation")
0d292a1e6d90 ("misc: pci_endpoint_test: Add support for capabilities")

My expectation is that DWC based endpoint controller drivers should no longer
need an explicit 4k alignment in the host side driver.

Thus, I would expect that:
{ PCI_DEVICE(PCI_VENDOR_ID_TESLA, 0x7777),},

(i.e. no explicit 4k alignment)
should be sufficient.

Kind regards,
Niklas