Re: [PATCH RESEND v3 3/6] i3c: mipi-i3c-hci: Add a quirk to set PIO mode

[Jarkko Nikula <jarkko.nikula@linux.intel.com>]

Hi

On 8/7/24 8:23 AM, Shyam Sundar S K wrote:
> The AMD HCI controller currently only supports PIO mode but exposes DMA
> rings to the OS, which leads to the controller being configured in DMA
> mode. To address this, add a quirk to avoid configuring the controller in
> DMA mode and default to PIO mode.
> 
> Additionally, introduce a generic quirk infrastructure to the mipi-i3c-hci
> driver to facilitate seamless future quirk additions.
> 
> Co-developed-by: Krishnamoorthi M <krishnamoorthi.m@amd.com>
> Signed-off-by: Krishnamoorthi M <krishnamoorthi.m@amd.com>
> Co-developed-by: Guruvendra Punugupati <Guruvendra.Punugupati@amd.com>
> Signed-off-by: Guruvendra Punugupati <Guruvendra.Punugupati@amd.com>
> Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
> ---

...

> +void amd_i3c_hci_quirks_init(struct i3c_hci *hci)
> +{
> +#if defined(CONFIG_X86)
> +	if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
> +		hci->quirks |= HCI_QUIRK_PIO_MODE;
> +#endif
> +}

I was thinking these quirks can be passed as driver_data more cleanly 
and be specific only to affected HW if AMD HW would have an unique ACPI 
ID for each HW version.

Above X86_VENDOR_AMD might be too generic if and when quirks are fixed 
in the future HW :-)

So something like:

static const struct acpi_device_id i3c_hci_acpi_match[] = {
	{"AMDI1234", HCI_QUIRK_PIO_MODE | HCI_QUIRK_OD_PP_TIMING | 
HCI_QUIRK_RESP_BUF_THLD},
	{}
};

and set them in the i3c_hci_probe() as:

hci->quirks = (unsigned long)device_get_match_data(&pdev->dev);