linux-kernel - Re: [PATCH 5/5] firmware: add DECLARE_FW_CUSTOM

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Date:   Fri, 16 Dec 2016 10:22:41 +0100
From:   "Luis R. Rodriguez" <mcgrof@...nel.org>
To:     Pavel Machek <pavel@....cz>
Cc:     "Luis R. Rodriguez" <mcgrof@...nel.org>,
        gregkh@...uxfoundation.org, ming.lei@...onical.com,
        daniel.wagner@...-carit.de, teg@...m.no, mchehab@....samsung.com,
        zajec5@...il.com, linux-kernel@...r.kernel.org,
        markivx@...eaurora.org, stephen.boyd@...aro.org,
        broonie@...nel.org, zohar@...ux.vnet.ibm.com, tiwai@...e.de,
        johannes@...solutions.net, chunkeey@...glemail.com,
        hauke@...ke-m.de, jwboyer@...oraproject.org,
        dmitry.torokhov@...il.com, dwmw2@...radead.org, jslaby@...e.com,
        torvalds@...ux-foundation.org, luto@...capital.net,
        fengguang.wu@...el.com, rpurdie@...ys.net,
        j.anaszewski@...sung.com, Abhay_Salunke@...l.com,
        Julia.Lawall@...6.fr, Gilles.Muller@...6.fr, nicolas.palix@...g.fr,
        dhowells@...hat.com, bjorn.andersson@...aro.org,
        arend.vanspriel@...adcom.com, kvalo@...eaurora.org,
        linux-leds@...r.kernel.org
Subject: Re: [PATCH 5/5] firmware: add DECLARE_FW_CUSTOM_FALLBACK() annotation

On Tue, Dec 13, 2016 at 08:04:29PM +0100, Pavel Machek wrote:
> Hi!
> 
> > We need to ensure that when driver developers use the custom firmware
> > fallback mechanism it was not a copy and paste bug. These use cases on
> > upstream drivers are rare, we only have 2 upstream users and its for
> > really old drivers. Since valid uses are rare but possible enable a
> > white-list for its use, and use this same white-list annotation to refer
> > to the documentation covering the custom use case.
> 
> > --- a/drivers/leds/leds-lp55xx-common.c
> > +++ b/drivers/leds/leds-lp55xx-common.c
> > @@ -219,6 +219,7 @@ static void lp55xx_firmware_loaded(const struct firmware *fw, void *context)
> >  	release_firmware(chip->fw);
> >  }
> >  
> > +DECLARE_FW_CUSTOM_FALLBACK("Documentation/leds/leds-lp55xx.txt");
> >  static int lp55xx_request_firmware(struct lp55xx_chip *chip)
> >  {
> >  	const char *name = chip->cl->name;
> 
> The driver does:
> 
> static void lp55xx_firmware_loaded(const struct firmware *fw, void
> *context)
> {
> 	struct lp55xx_chip *chip = context;
> 	        struct device *dev = &chip->cl->dev;
> 		        enum lp55xx_engine_index idx =
> 			chip->engine_idx;
> 
>         if (!fw) {
> 	                dev_err(dev, "firmware request failed\n");
> 			                goto out;
> 					     }
>         ...
> out:
>         /* firmware should be released for other channel use */
> 	        release_firmware(chip->fw);
> }
> 
> 
> Does that match the "custom fallback" definition?

Refer to the documentation I supplied, and also to the grammar rule, in
particular the patch "firmware: add SmPL report for custom fallback mechanism",
it captures the SmPL form for the custom fallback mechanism as:

@ r1 depends on report || context @                                             
expression mod, name, dev, gfp, drv, cb;                                        
position p;                                                                     
@@                                                                              
                                                                                
(                                                                               
*request_firmware_nowait@p(mod, false, name, dev, gfp, drv, cb)                 
|                                                                               
*request_firmware_nowait@p(mod, 0, name, dev, gfp, drv, cb)                     
|                                                                               
*request_firmware_nowait@p(mod, FW_ACTION_NOHOTPLUG, name, dev, gfp, drv, cb)   
)