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 <jacopo+renesas@xxxxxxxxxx>
> >> ---
> >> 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
