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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <2a9f6c23-9c7b-496b-9998-ea0afe526b46@linux.intel.com>
Date: Fri, 9 Aug 2024 16:55:41 +0300
From: Jarkko Nikula <jarkko.nikula@...ux.intel.com>
To: Shyam Sundar S K <Shyam-sundar.S-k@....com>,
 Alexandre Belloni <alexandre.belloni@...tlin.com>
Cc: Guruvendra Punugupati <Guruvendra.Punugupati@....com>,
 Krishnamoorthi M <krishnamoorthi.m@....com>, linux-i3c@...ts.infradead.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH RESEND v3 3/6] i3c: mipi-i3c-hci: Add a quirk to set PIO
 mode

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@....com>
> Signed-off-by: Krishnamoorthi M <krishnamoorthi.m@....com>
> Co-developed-by: Guruvendra Punugupati <Guruvendra.Punugupati@....com>
> Signed-off-by: Guruvendra Punugupati <Guruvendra.Punugupati@....com>
> Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@....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);