From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753916AbeDZT5B (ORCPT ); Thu, 26 Apr 2018 15:57:01 -0400 Received: from perceval.ideasonboard.com ([213.167.242.64]:59150 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751496AbeDZT47 (ORCPT ); Thu, 26 Apr 2018 15:56:59 -0400 From: Laurent Pinchart To: jacopo mondi Cc: Jacopo Mondi , architt@codeaurora.org, a.hajda@samsung.com, airlied@linux.ie, daniel@ffwll.ch, peda@axentia.se, linux-renesas-soc@vger.kernel.org, linux-media@vger.kernel.org, devicetree@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/8] drm: bridge: Add support for static image formats Date: Thu, 26 Apr 2018 22:57:11 +0300 Message-ID: <4630637.CPzkxH2bjR@avalon> Organization: Ideas on Board Oy In-Reply-To: <20180426184056.GQ4235@w540> References: <1524130269-32688-1-git-send-email-jacopo+renesas@jmondi.org> <3108314.q4SV6s3NXE@avalon> <20180426184056.GQ4235@w540> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Jacopo, On Thursday, 26 April 2018 21:40:56 EEST jacopo mondi wrote: > On Mon, Apr 23, 2018 at 12:27:39PM +0300, Laurent Pinchart wrote: > > On Thursday, 19 April 2018 12:31:02 EEST Jacopo Mondi wrote: > >> Add support for storing image format information in DRM bridges with > >> associated helper function. > >> > >> This patch replicates for bridges what > >> 'drm_display_info_set_bus_formats()' > >> is for connectors. > >> > >> Signed-off-by: Jacopo Mondi > >> --- > >> drivers/gpu/drm/drm_bridge.c | 30 ++++++++++++++++++++++++++++++ > >> include/drm/drm_bridge.h | 8 ++++++++ > >> 2 files changed, 38 insertions(+) > >> > >> diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c > >> index 1638bfe..e2ad098 100644 > >> --- a/drivers/gpu/drm/drm_bridge.c > >> +++ b/drivers/gpu/drm/drm_bridge.c > >> @@ -157,6 +157,36 @@ void drm_bridge_detach(struct drm_bridge *bridge) > >> } > >> > >> /** > >> + * drm_bridge_set_bus_formats() - set bridge supported image formats > >> + * @bridge: the bridge to set image formats in > >> + * @formats: array of MEDIA_BUS_FMT\_ supported image formats > > > > Why the \ (here and below) ? > > mmm, I can't tell where I made that up from... Will change with > MEDIA_BUS_FMT_* > > >> + * @num_formats: number of elements in the @formats array > >> + * > >> + * Store a list of supported image formats in a bridge. > >> + * See MEDIA_BUS_FMT_* definitions in > >> include/uapi/linux/media-bus-format.h for > >> + * a full list of available formats. > >> + */ > >> +int drm_bridge_set_bus_formats(struct drm_bridge *bridge, const u32 > >> *formats, > >> + unsigned int num_formats) > >> +{ > >> + u32 *fmts; > >> + > >> + if (!formats || !num_formats) > >> + return -EINVAL; > >> + > >> + fmts = kmemdup(formats, sizeof(*formats) * num_formats, GFP_KERNEL); > > > > This memory will be leaked when the bridge is destroyed. > > Right. I'm afraid this may open a pandora box, but, ehm, where is the > bridge objects lifetime managed? The best I can think of is to use the > resource managed version of kmemdup, associating that memory to > the drm_device device object. That means the memory will be freed at > DRM pipeline teardown time only if I'm not wrong. Can a bridge be > destroyed before that? The lifetime of the bridge is independent from the lifetime of the drm_device, so that won't work. It looks like we need to add a bridge cleanup operation :-/ You're right, it opens pandora's box. My recommendation is to add a .release() operation to the bridge ops structure, and to implement a drm_bridge_cleanup() function that frees the bus_formats memory. Then, a drm_bridge_release() function can wrap the release() ops, and that should be called from the bridge driver .remove() handler. Or even butter, call the drm_bridge_release() function drm_bridge_put(), to pave the way for a reference-count-based implementation. > >> + if (!fmts) > >> + return -ENOMEM; > >> + > >> + kfree(bridge->bus_formats); > >> + bridge->bus_formats = fmts; > >> + bridge->num_bus_formats = num_formats; > >> + > >> + return 0; > >> +} > >> +EXPORT_SYMBOL(drm_bridge_set_bus_formats); > >> + > >> +/** > >> * DOC: bridge callbacks > >> * > >> * The &drm_bridge_funcs ops are populated by the bridge driver. The > >> DRM > >> diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h > >> index 3270fec..6b3648c 100644 > >> --- a/include/drm/drm_bridge.h > >> +++ b/include/drm/drm_bridge.h > >> @@ -258,6 +258,9 @@ struct drm_bridge_timings { > >> * @encoder: encoder to which this bridge is connected > >> * @next: the next bridge in the encoder chain > >> * @of_node: device node pointer to the bridge > >> + * @bus_formats: wire image formats. Array of @num_bus_formats > >> MEDIA_BUS_FMT\_ > >> + * elements > >> + * @num_bus_formats: size of @bus_formats array > >> * @list: to keep track of all added bridges > >> * @timings: the timing specification for the bridge, if any (may > >> * be NULL) > >> @@ -271,6 +274,9 @@ struct drm_bridge { > >> #ifdef CONFIG_OF > >> struct device_node *of_node; > >> #endif > >> + const u32 *bus_formats; > >> + unsigned int num_bus_formats; > >> + > >> struct list_head list; > >> const struct drm_bridge_timings *timings; > >> > >> @@ -296,6 +302,8 @@ void drm_bridge_mode_set(struct drm_bridge *bridge, > >> struct drm_display_mode *adjusted_mode); > >> void drm_bridge_pre_enable(struct drm_bridge *bridge); > >> void drm_bridge_enable(struct drm_bridge *bridge); > >> +int drm_bridge_set_bus_formats(struct drm_bridge *bridge, const u32 > >> *fmts, > >> + unsigned int num_fmts); > >> > >> #ifdef CONFIG_DRM_PANEL_BRIDGE > >> struct drm_bridge *drm_panel_bridge_add(struct drm_panel *panel, -- Regards, Laurent Pinchart