From: Jacek Anaszewski <j.anaszewski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org> To: Pavel Machek <pavel-+ZI9xUNit7I@public.gmane.org> Cc: linux-leds-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-media-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kyungmin.park-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org, b.zolnierkie-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org, cooloney-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, rpurdie-Fm38FmjxZ/leoWH0uzbU5w@public.gmane.org, sakari.ailus-X3B1VOXEql0@public.gmane.org, s.nawrocki-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org, Hans Verkuil <hans.verkuil-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org> Subject: Re: [PATCH/RFC v10 15/19] media: Add registration helpers for V4L2 flash sub-devices Date: Mon, 12 Jan 2015 10:46:26 +0100 [thread overview] Message-ID: <54B397F2.6060205@samsung.com> (raw) In-Reply-To: <20150109205432.GP18076@amd> Hi Pavel, Thanks for the review. On 01/09/2015 09:54 PM, Pavel Machek wrote: > On Fri 2015-01-09 16:23:05, Jacek Anaszewski wrote: >> This patch adds helper functions for registering/unregistering >> LED Flash class devices as V4L2 sub-devices. The functions should >> be called from the LED subsystem device driver. In case the >> support for V4L2 Flash sub-devices is disabled in the kernel >> config the functions' empty versions will be used. >> >> Signed-off-by: Jacek Anaszewski <j.anaszewski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org> >> Acked-by: Kyungmin Park <kyungmin.park-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org> >> Cc: Sakari Ailus <sakari.ailus-X3B1VOXEql0@public.gmane.org> >> Cc: Hans Verkuil <hans.verkuil-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org> > > Acked-by: Pavel Machek <pavel-+ZI9xUNit7I@public.gmane.org> > >> + /* >> + * Indicator leds, unlike torch leds, are turned on/off basing >> on > > leds -> LEDs. Sure. >> + * the state of V4L2_CID_FLASH_INDICATOR_INTENSITY control only. >> + * Therefore it must be possible to set it to 0 level which in >> + * the LED subsystem reflects LED_OFF state. >> + */ >> + if (cdata_id != INDICATOR_INTENSITY) >> + ++__intensity; > > And normally we'd do i++ instead of ++i, and avoid __ for local > variables...? Pre-incrementation operator is favourable over the post-incrementation one if we don't want to have an access to the value of a variable before incrementation, which is the case here. Maybe gcc detects the cases when the value of a variable is not assigned and doesn't copy it before incrementing, however I haven't found any reference. I see that often in the for loops the i++ version is used, but I am not sure if this is done because developers are aware that gcc will optimize it anyway or it is just an omission. And regarding __ for local variable - I haven't found any restriction about it in the Documentation/CodingStyle. Nevertheless I can rename it to tmp or something. >> +/** >> + * struct v4l2_flash_ctrl_config - V4L2 Flash controls initialization data >> + * @intensity: constraints for the led in a non-flash mode >> + * @flash_intensity: V4L2_CID_FLASH_INTENSITY settings constraints >> + * @flash_timeout: V4L2_CID_FLASH_TIMEOUT constraints >> + * @flash_faults: possible flash faults >> + * @has_external_strobe: external strobe capability >> + * @indicator_led: signifies that a led is of indicator type >> + */ >> +struct v4l2_flash_ctrl_config { >> + struct v4l2_ctrl_config intensity; >> + struct v4l2_ctrl_config flash_intensity; >> + struct v4l2_ctrl_config flash_timeout; >> + u32 flash_faults; >> + bool has_external_strobe:1; >> + bool indicator_led:1; >> +}; > > I don't think you are supposed to do boolean bit arrays. These bit fields allow to reduce memory usage. If they were not bit fields, the address of the next variable would be aligned to the multiply of the CPU word size. Please look e.g. at struct dev_pm_info in the file include/linux/pm.h. It also contains boolean bit fields. -- Best Regards, Jacek Anaszewski -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html
WARNING: multiple messages have this Message-ID (diff)
From: Jacek Anaszewski <j.anaszewski@samsung.com> To: Pavel Machek <pavel@ucw.cz> Cc: linux-leds@vger.kernel.org, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, kyungmin.park@samsung.com, b.zolnierkie@samsung.com, cooloney@gmail.com, rpurdie@rpsys.net, sakari.ailus@iki.fi, s.nawrocki@samsung.com, Hans Verkuil <hans.verkuil@cisco.com> Subject: Re: [PATCH/RFC v10 15/19] media: Add registration helpers for V4L2 flash sub-devices Date: Mon, 12 Jan 2015 10:46:26 +0100 [thread overview] Message-ID: <54B397F2.6060205@samsung.com> (raw) In-Reply-To: <20150109205432.GP18076@amd> Hi Pavel, Thanks for the review. On 01/09/2015 09:54 PM, Pavel Machek wrote: > On Fri 2015-01-09 16:23:05, Jacek Anaszewski wrote: >> This patch adds helper functions for registering/unregistering >> LED Flash class devices as V4L2 sub-devices. The functions should >> be called from the LED subsystem device driver. In case the >> support for V4L2 Flash sub-devices is disabled in the kernel >> config the functions' empty versions will be used. >> >> Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com> >> Acked-by: Kyungmin Park <kyungmin.park@samsung.com> >> Cc: Sakari Ailus <sakari.ailus@iki.fi> >> Cc: Hans Verkuil <hans.verkuil@cisco.com> > > Acked-by: Pavel Machek <pavel@ucw.cz> > >> + /* >> + * Indicator leds, unlike torch leds, are turned on/off basing >> on > > leds -> LEDs. Sure. >> + * the state of V4L2_CID_FLASH_INDICATOR_INTENSITY control only. >> + * Therefore it must be possible to set it to 0 level which in >> + * the LED subsystem reflects LED_OFF state. >> + */ >> + if (cdata_id != INDICATOR_INTENSITY) >> + ++__intensity; > > And normally we'd do i++ instead of ++i, and avoid __ for local > variables...? Pre-incrementation operator is favourable over the post-incrementation one if we don't want to have an access to the value of a variable before incrementation, which is the case here. Maybe gcc detects the cases when the value of a variable is not assigned and doesn't copy it before incrementing, however I haven't found any reference. I see that often in the for loops the i++ version is used, but I am not sure if this is done because developers are aware that gcc will optimize it anyway or it is just an omission. And regarding __ for local variable - I haven't found any restriction about it in the Documentation/CodingStyle. Nevertheless I can rename it to tmp or something. >> +/** >> + * struct v4l2_flash_ctrl_config - V4L2 Flash controls initialization data >> + * @intensity: constraints for the led in a non-flash mode >> + * @flash_intensity: V4L2_CID_FLASH_INTENSITY settings constraints >> + * @flash_timeout: V4L2_CID_FLASH_TIMEOUT constraints >> + * @flash_faults: possible flash faults >> + * @has_external_strobe: external strobe capability >> + * @indicator_led: signifies that a led is of indicator type >> + */ >> +struct v4l2_flash_ctrl_config { >> + struct v4l2_ctrl_config intensity; >> + struct v4l2_ctrl_config flash_intensity; >> + struct v4l2_ctrl_config flash_timeout; >> + u32 flash_faults; >> + bool has_external_strobe:1; >> + bool indicator_led:1; >> +}; > > I don't think you are supposed to do boolean bit arrays. These bit fields allow to reduce memory usage. If they were not bit fields, the address of the next variable would be aligned to the multiply of the CPU word size. Please look e.g. at struct dev_pm_info in the file include/linux/pm.h. It also contains boolean bit fields. -- Best Regards, Jacek Anaszewski
next prev parent reply other threads:[~2015-01-12 9:46 UTC|newest] Thread overview: 107+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-01-09 15:22 [PATCH/RFC v10 00/19] LED / flash API integration Jacek Anaszewski 2015-01-09 15:22 ` [PATCH/RFC v10 01/19] leds: Add LED Flash class extension to the LED subsystem Jacek Anaszewski 2015-01-09 17:37 ` Pavel Machek 2015-01-26 23:02 ` Bryan Wu 2015-01-09 15:22 ` [PATCH/RFC v10 02/19] Documentation: leds: Add description of LED Flash class extension Jacek Anaszewski 2015-01-09 17:40 ` Pavel Machek 2015-01-12 8:04 ` Jacek Anaszewski 2015-01-26 23:03 ` Bryan Wu 2015-01-09 15:22 ` [PATCH/RFC v10 03/19] DT: leds: Add led-sources property Jacek Anaszewski 2015-01-09 17:42 ` Pavel Machek [not found] ` <1420816989-1808-4-git-send-email-j.anaszewski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org> 2015-01-09 18:33 ` Rob Herring 2015-01-09 18:33 ` Rob Herring 2015-01-12 8:32 ` Jacek Anaszewski 2015-01-12 13:52 ` Rob Herring 2015-01-12 16:10 ` Jacek Anaszewski 2015-01-12 16:55 ` Rob Herring 2015-01-12 17:06 ` Mark Brown 2015-01-15 12:33 ` Sylwester Nawrocki 2015-01-15 14:37 ` Rob Herring 2015-01-15 21:03 ` Pavel Machek 2015-01-16 10:17 ` Sylwester Nawrocki 2015-01-16 10:17 ` Sylwester Nawrocki [not found] ` <CAL_JsqKpJtUG0G6g1GOuSVpc31oe-dp3qdrKJUE0upG-xRDFhA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org> 2015-01-13 8:42 ` Jacek Anaszewski 2015-01-13 8:42 ` Jacek Anaszewski 2015-01-15 14:24 ` Rob Herring 2015-01-15 15:53 ` Mark Brown 2015-01-16 9:07 ` Jacek Anaszewski 2015-01-16 13:48 ` Rob Herring [not found] ` <CAL_Jsq+EFWzs1HP1tVt6P=p=HZn2AtSPjp55YrmMQi_mE+kNfQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org> 2015-01-16 15:52 ` Jacek Anaszewski 2015-01-16 15:52 ` Jacek Anaszewski 2015-01-20 16:09 ` Jacek Anaszewski 2015-01-20 17:29 ` Rob Herring 2015-01-20 17:40 ` Pavel Machek 2015-01-21 9:39 ` Jacek Anaszewski 2015-01-28 7:04 ` Sakari Ailus 2015-01-09 15:22 ` [PATCH/RFC v10 04/19] dt-binding: mfd: max77693: Add DT binding related macros Jacek Anaszewski 2015-01-09 17:43 ` Pavel Machek 2015-01-20 11:12 ` Lee Jones 2015-01-20 12:53 ` Jacek Anaszewski 2015-01-28 8:52 ` Sakari Ailus 2015-01-09 15:22 ` [PATCH/RFC v10 05/19] mfd: max77693: Modify flash cell name identifiers Jacek Anaszewski 2015-01-09 17:53 ` Pavel Machek [not found] ` <1420816989-1808-6-git-send-email-j.anaszewski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org> 2015-01-20 11:13 ` Lee Jones 2015-01-20 11:13 ` Lee Jones 2015-01-20 12:57 ` Jacek Anaszewski 2015-01-20 12:57 ` Jacek Anaszewski 2015-01-20 15:41 ` Lee Jones 2015-01-09 15:22 ` [PATCH/RFC v10 06/19] mfd: max77693: modifications around max77693_led_platform_data Jacek Anaszewski 2015-01-09 17:56 ` Pavel Machek [not found] ` <1420816989-1808-7-git-send-email-j.anaszewski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org> 2015-01-20 11:15 ` Lee Jones 2015-01-20 11:15 ` Lee Jones 2015-01-09 15:22 ` [PATCH/RFC v10 07/19] mfd: max77693: Adjust FLASH_EN_SHIFT and TORCH_EN_SHIFT macros Jacek Anaszewski 2015-01-09 17:59 ` Pavel Machek 2015-01-20 11:17 ` Lee Jones 2015-01-20 13:01 ` Jacek Anaszewski 2015-01-20 14:11 ` Jacek Anaszewski 2015-01-20 15:40 ` Lee Jones 2015-01-20 16:00 ` Pavel Machek 2015-01-20 16:41 ` Lee Jones 2015-01-09 15:22 ` [PATCH/RFC v10 08/19] leds: Add support for max77693 mfd flash cell Jacek Anaszewski [not found] ` <1420816989-1808-9-git-send-email-j.anaszewski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org> 2015-01-09 18:46 ` Pavel Machek 2015-01-09 18:46 ` Pavel Machek 2015-01-12 8:52 ` Jacek Anaszewski 2015-01-12 13:25 ` Pavel Machek 2015-01-12 13:46 ` Jacek Anaszewski 2015-02-05 15:34 ` Sakari Ailus 2015-02-05 15:34 ` Sakari Ailus 2015-02-05 16:26 ` Jacek Anaszewski 2015-01-09 15:22 ` [PATCH/RFC v10 09/19] DT: Add documentation for the mfd Maxim max77693 Jacek Anaszewski 2015-01-09 17:52 ` Pavel Machek 2015-01-20 11:21 ` Lee Jones 2015-01-20 14:36 ` Jacek Anaszewski [not found] ` <54BE67EA.2070507-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org> 2015-01-20 15:38 ` Lee Jones 2015-01-20 15:38 ` Lee Jones [not found] ` <1420816989-1808-1-git-send-email-j.anaszewski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org> 2015-01-09 15:23 ` [PATCH/RFC v10 10/19] leds: Add driver for AAT1290 current regulator Jacek Anaszewski 2015-01-09 15:23 ` Jacek Anaszewski [not found] ` <1420816989-1808-11-git-send-email-j.anaszewski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org> 2015-01-09 18:57 ` Pavel Machek 2015-01-09 18:57 ` Pavel Machek 2015-01-09 15:23 ` [PATCH/RFC v10 11/19] of: Add Skyworks Solutions, Inc. vendor prefix Jacek Anaszewski [not found] ` <1420816989-1808-12-git-send-email-j.anaszewski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org> 2015-01-09 18:57 ` Pavel Machek 2015-01-09 18:57 ` Pavel Machek 2015-01-09 15:23 ` [PATCH/RFC v10 12/19] DT: Add documentation for the Skyworks AAT1290 Jacek Anaszewski 2015-01-09 18:58 ` Pavel Machek 2015-01-09 15:23 ` [PATCH/RFC v10 13/19] exynos4-is: Add support for v4l2-flash subdevs Jacek Anaszewski 2015-01-09 19:06 ` Pavel Machek 2015-01-09 15:23 ` [PATCH/RFC v10 14/19] v4l2-ctrls: Add V4L2_CID_FLASH_SYNC_STROBE control Jacek Anaszewski [not found] ` <1420816989-1808-15-git-send-email-j.anaszewski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org> 2015-01-09 19:06 ` Pavel Machek 2015-01-09 19:06 ` Pavel Machek 2015-02-05 16:36 ` Sakari Ailus 2015-01-09 15:23 ` [PATCH/RFC v10 15/19] media: Add registration helpers for V4L2 flash sub-devices Jacek Anaszewski 2015-01-09 20:54 ` Pavel Machek 2015-01-12 9:46 ` Jacek Anaszewski [this message] 2015-01-12 9:46 ` Jacek Anaszewski 2015-01-12 13:27 ` Pavel Machek 2015-02-05 17:59 ` Sakari Ailus 2015-02-09 11:15 ` Jacek Anaszewski 2015-01-09 15:23 ` [PATCH/RFC v10 16/19] Documentation: leds: Add description of v4l2-flash sub-device Jacek Anaszewski 2015-01-09 20:57 ` Pavel Machek 2015-01-09 15:23 ` [PATCH/RFC v10 17/19] DT: Add documentation for exynos4-is 'flashes' property Jacek Anaszewski 2015-01-09 20:57 ` Pavel Machek 2015-01-21 16:32 ` Sylwester Nawrocki 2015-01-22 8:47 ` Jacek Anaszewski 2015-01-09 15:23 ` [PATCH/RFC v10 18/19] leds: max77693: add support for V4L2 Flash sub-device Jacek Anaszewski 2015-01-09 20:59 ` Pavel Machek 2015-01-09 15:23 ` [PATCH/RFC v10 19/19] leds: aat1290: " Jacek Anaszewski [not found] ` <1420816989-1808-20-git-send-email-j.anaszewski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org> 2015-01-09 20:59 ` Pavel Machek 2015-01-09 20:59 ` Pavel Machek
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