On Thu, May 16, 2024 at 06:40:45PM GMT, Sui Jingfeng wrote: > Hi, > > On 5/16/24 16:25, Maxime Ripard wrote: > > On Wed, May 15, 2024 at 11:19:58PM +0800, Sui Jingfeng wrote: > > > Hi, > > > > > > > > > On 5/15/24 22:58, Maxime Ripard wrote: > > > > On Wed, May 15, 2024 at 10:53:00PM +0800, Sui Jingfeng wrote: > > > > > On 5/15/24 22:30, Maxime Ripard wrote: > > > > > > On Wed, May 15, 2024 at 12:53:33AM +0800, Sui Jingfeng wrote: > > > > > > > On 2024/5/15 00:22, Maxime Ripard wrote: > > > > > > > > Hi, > > > > > > > > > > > > > > > > On Tue, May 14, 2024 at 11:40:43PM +0800, Sui Jingfeng wrote: > > > > > > > > > Because a lot of implementations has already added it into their drived > > > > > > > > > class, promote it into drm_bridge core may benifits a lot. drm bridge is > > > > > > > > > a driver, it should know the underlying hardware entity. > > > > > > > > Is there some actual benefits, or is it theoretical at this point? > > > > > > > > > > > > > > > > > > > > > I think, DRM bridge drivers could remove the 'struct device *dev' > > > > > > > member from their derived structure. Rely on the drm bridge core > > > > > > > when they need the 'struct device *' pointer. > > > > > > > > > > > > Sure, but why do we need to do so? > > > > > > > > > > > > The other thread you had with Jani points out that it turns out that > > > > > > things are more complicated than "every bridge driver has a struct > > > > > > device anyway", it creates inconsistency in the API (bridges would have > > > > > > a struct device, but not other entities), and it looks like there's no > > > > > > use for it anyway. > > > > > > > > > > > > None of these things are deal-breaker by themselves, but if there's only > > > > > > downsides and no upside, it's not clear to me why we should do it at all. > > > > > > > > > > It can reduce boilerplate. > > > > > > > > You're still using a conditional here. > > > > > > It's for safety reason, prevent NULL pointer dereference. > > > drm bridge can be seen as either a software entity or a device driver. > > > > > > It's fine to pass NULL if specific KMS drivers intend to see > > > drm bridge as a pure software entity, and for internal use only. > > > Both use cases are valid. > > > > Sorry, I don't follow you. We can't NULL dereference a pointer that > > doesn't exist. > > > > Please state why we should merge this series: what does it fix or > > improve, aside from the potential gain of making bridges declare one > > less pointer in their private structure. > > We could reduce more. But *why*? What benefit does it bring that outweights the downsides I listed earlier? > Bridge driver instances also don't have to embed 'struct i2c_client *'. We > could use 'to_i2c_client(bridge->dev)' to retrieve the pointer, > where needed. Sure, we could use a function instead of another one. But again, what benefit does that bring exactly?
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