linux-kernel - Re: [PATCH] usb: xhci: avoid renesas_usb

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Message-Id: <xr93czs1p4uj.fsf@gthelen2.svl.corp.google.com>
Date:   Fri, 02 Jul 2021 00:11:48 -0700
From:   Greg Thelen <gthelen@...gle.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Vinod Koul <vkoul@...nel.org>,
        Mathias Nyman <mathias.nyman@...el.com>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] usb: xhci: avoid renesas_usb_fw.mem when it's unusable

Greg Kroah-Hartman <gregkh@...uxfoundation.org> wrote:

> On Thu, Jul 01, 2021 at 10:47:54PM -0700, Greg Thelen wrote:
>> Commit a66d21d7dba8 ("usb: xhci: Add support for Renesas controller with
>> memory") added renesas_usb_fw.mem firmware reference to xhci-pci.  Thus
>> modinfo indicates xhci-pci.ko has "firmware: renesas_usb_fw.mem".  But
>> the firmware is only actually used with CONFIG_USB_XHCI_PCI_RENESAS.  An
>> unusable firmware reference can trigger safety checkers which look for
>> drivers with unmet firmware dependencies.
>> 
>> Avoid referring to renesas_usb_fw.mem in circumstances when it cannot be
>> loaded (when CONFIG_USB_XHCI_PCI_RENESAS isn't set).
>> 
>> Signed-off-by: Greg Thelen <gthelen@...gle.com>
>> ---
>>  drivers/usb/host/xhci-pci.c | 8 ++++++++
>>  1 file changed, 8 insertions(+)
>> 
>> diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c
>> index 18c2bbddf080..cb148da7a789 100644
>> --- a/drivers/usb/host/xhci-pci.c
>> +++ b/drivers/usb/host/xhci-pci.c
>> @@ -618,8 +618,10 @@ static void xhci_pci_shutdown(struct usb_hcd *hcd)
>>  /*-------------------------------------------------------------------------*/
>>  
>>  static const struct xhci_driver_data reneses_data = {
>> +#if IS_ENABLED(CONFIG_USB_XHCI_PCI_RENESAS)
>
> If this is not enabled, why is the whole structure needed?

Removing the struct meant 2 more #if guards needed below to initialize
pci_ids, which exceeded my taste.

>>  	.quirks  = XHCI_RENESAS_FW_QUIRK,
>>  	.firmware = "renesas_usb_fw.mem",
>> +#endif
>>  };
>>  
>>  /* PCI driver selection metadata; PCI hotplugging uses this */
>> @@ -636,7 +638,13 @@ static const struct pci_device_id pci_ids[] = {
>>  	{ /* end: all zeroes */ }
>>  };
>>  MODULE_DEVICE_TABLE(pci, pci_ids);
>> +/*
>> + * Without CONFIG_USB_XHCI_PCI_RENESAS renesas_xhci_check_request_fw() won't
>> + * load firmware, so don't encumber the xhci-pci driver with it.
>> + */
>> +#if IS_ENABLED(CONFIG_USB_XHCI_PCI_RENESAS)
>>  MODULE_FIRMWARE("renesas_usb_fw.mem");
>> +#endif
>
> Why not just have this one chunk, why is the first chunk needed?

It seemed cleaner to remove both renesas_usb_fw.mem references rather
than leave one unusable one in reneses_data above.  But a simpler patch
is appealing, especially given the number of #if guards needed to remove
reneses_data.  Patch V2 will just go with this 1-hunk approach.

> And a blank line please before your comment?

Will do.

> And can you add a Fixes: line to the changelog text when you resend?

Will do.

> thanks,
>
> greg k-h