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From: Andrzej Hajda <a.hajda@samsung.com>
To: Grygorii Strashko <grygorii.strashko@ti.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jernej Skrabec <jernej.skrabec@siol.net>,
	Jonas Karlman <jonas@kwiboo.se>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
	Russell King - ARM Linux <linux@armlinux.org.uk>,
	"open list:DRM DRIVERS" <dri-devel@lists.freedesktop.org>,
	linux-kernel@vger.kernel.org,
	Neil Armstrong <narmstrong@baylibre.com>,
	andy.shevchenko@gmail.com, Mark Brown <broonie@kernel.org>,
	Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	linux-arm-kernel@lists.infradead.org,
	Marek Szyprowski <m.szyprowski@samsung.com>
Subject: Re: [PATCH v6 2/4] driver core: add deferring probe reason to devices_deferred property
Date: Tue, 30 Jun 2020 17:41:26 +0200
Message-ID: <21f5ec9c-2d1d-5f28-5aeb-ac0db144a55e@samsung.com> (raw)
In-Reply-To: <66faa188-5ef6-d449-07fe-28c8be5e559c@ti.com>


On 30.06.2020 10:59, Grygorii Strashko wrote:
> Hi
>
> On 29/06/2020 14:28, Andrzej Hajda wrote:
>> Hi Grygorii,
>>
>> (...)
>>
>>>>    /*
>>>>     * deferred_devs_show() - Show the devices in the deferred probe
>>>> pending list.
>>>>     */
>>>> @@ -221,7 +241,8 @@ static int deferred_devs_show(struct seq_file *s,
>>>> void *data)
>>>>        mutex_lock(&deferred_probe_mutex);
>>>>          list_for_each_entry(curr, &deferred_probe_pending_list,
>>>> deferred_probe)
>>>> -        seq_printf(s, "%s\n", dev_name(curr->device));
>>>> +        seq_printf(s, "%s\t%s", dev_name(curr->device),
>>>> + curr->device->p->deferred_probe_reason ?: "\n");
>>>>          mutex_unlock(&deferred_probe_mutex);
>>>>
>>>
>>> Sry, may be i missing smth, but shouldn't it be optional
>>> (CONFIG_DEBUG_FS is probably too generic).
>>>
>>
>> I am not sure what exactly are you referring to, but this patch does not
>> add new property, it just extends functionality of existing one.
>
> Sry, needed to be more specific.
>
> You've added  device_set_deferred_probe_reson(dev, &vaf);
> which expected to be used on every EPROBE_DEFER in dev_err_probe() in 
> combination with
>
> +       } else {
> +               device_set_deferred_probe_reson(dev, &vaf);
>                 dev_dbg(dev, "error %d: %pV", err, &vaf);
>
> ^^ dev_dbg() does not add any runtime overhead during boot unless enabled
> +       }
>
> But:
>
> +void device_set_deferred_probe_reson(const struct device *dev, struct 
> va_format *vaf)
> +{
> +       const char *drv = dev_driver_string(dev);
> +
> +       mutex_lock(&deferred_probe_mutex);
> +
> +       kfree(dev->p->deferred_probe_reason);
> +       dev->p->deferred_probe_reason = kasprintf(GFP_KERNEL, "%s: 
> %pV", drv, vaf);
> +
> +       mutex_unlock(&deferred_probe_mutex);
> +}
>
> ^^ Adds locking, kfree() and kasprintf() for every deferred probe 
> during boot and can't be disabled.
>
> Right?


Right, but usually the burden should be insignificant in comparison to 
probe time, so I do not think it is worth optimizing.


Regards

Andrzej


>
>

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Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20200626100108eucas1p2c6d68625f3755a467d7316dd27704f7c@eucas1p2.samsung.com>
2020-06-26 10:00 ` [PATCH v6 0/4] driver core: add probe error check helper Andrzej Hajda
     [not found]   ` <CGME20200626100109eucas1p25331652d017cd17d21c0ae60541d1f73@eucas1p2.samsung.com>
2020-06-26 10:01     ` [PATCH v6 1/4] driver core: add device probe log helper Andrzej Hajda
2020-06-26 15:41       ` Rafael J. Wysocki
2020-06-26 16:22       ` Sam Ravnborg
2020-07-01  9:29       ` Grygorii Strashko
     [not found]   ` <CGME20200626100110eucas1p2c5b91f2c98a5c6e5739f5af3207d192e@eucas1p2.samsung.com>
2020-06-26 10:01     ` [PATCH v6 2/4] driver core: add deferring probe reason to devices_deferred property Andrzej Hajda
2020-06-26 15:43       ` Rafael J. Wysocki
2020-06-26 17:11       ` Grygorii Strashko
2020-06-29 11:28         ` Andrzej Hajda
2020-06-30  8:59           ` Grygorii Strashko
2020-06-30 15:41             ` Andrzej Hajda [this message]
2020-06-30 18:00               ` Dmitry Torokhov
2020-07-02  6:57                 ` Andrzej Hajda
2020-07-07  4:14                   ` Dmitry Torokhov
2020-07-10  7:42                     ` Andrzej Hajda
2020-07-10 11:07                       ` Mark Brown
     [not found]   ` <CGME20200626100110eucas1p24327c924dada0c2e86ecf0ab5b5af571@eucas1p2.samsung.com>
2020-06-26 10:01     ` [PATCH v6 3/4] drm/bridge/sii8620: fix resource acquisition error handling Andrzej Hajda
2020-06-29  8:33       ` Neil Armstrong
     [not found]   ` <CGME20200626100111eucas1p18e175e6c77af483bd80fb90c171b05db@eucas1p1.samsung.com>
2020-06-26 10:01     ` [PATCH v6 4/4] drm/bridge: lvds-codec: simplify " Andrzej Hajda
2020-06-29  8:33       ` Neil Armstrong

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