media: ov6650: Fix set format try processing path
According to subdevice interface specification found in V4L2 API documentation, set format pad operations should not affect image geometry set in preceding image processing steps. Unfortunately, that requirement is not respected by the driver implementation of set format as it was not the case when that code was still implementing a pair of now obsolete .s_mbus_fmt() / .try_mbus_fmt() video operations before they have been merged and reused as an implementation of .set_fmt() pad operation by commit 717fd5b4 ("[media] v4l2: replace try_mbus_fmt by set_fmt"). In case of set format active processing path the issue can be fixed easily by excluding a call to set active selection from that path. That will effectively limit frame size processing to optimal frame scaling against active crop rectangle without touching it. Users can just call set active selection themselves to obtain desired frame size. However, set format try processing path needs more work. First of all, the driver should be extended with set try selection support. Lack of it constraints video device drivers to not use subdevice cropping at all while processing user requested active frame size, otherwise their set try format results might differ from active. Next, set format try processing path should use pad config crop rectangle as a reference, not the active one as it does now. That issue can be resolved easily as soon as set try selection support is added to the driver so pad config crop rectangle can be maintained by users via selection API. Last, set format try processing path should give the same results as active in respect to active vs. pad config crop rectangle geometry. Both rectangles should be either not touched by set format (that's what we are going to achieve) or modified the same way, otherwise users won't be able to obtain equal results from both paths while iterating through set format and set selection operations in order to obtain desired frame size. We can't begin with modifying set format pad operation as not to touch crop rectangle since that depends on availability of set try selection for symmetry. Neither can we begin with adding set try selection since that in turn depends on equal handling of active and pad config crop rectangles by set format. We can either implement all required modifications in a single patch, or begin with fixing current set format try processing path to appropriately handle pad config crop rectangle. This patch implements the latter approach as believed to be more readable. Move crop rectangle adjustments code from a helper (the former implementation of .s_fmt(), now called from set format active processing path) to the body of set format pad operation function where it can be also used for processing try requests for symmetry with active ones. As the helper no longer processes frame geometry, only frame format and half scaling, simplify its API accordingly and update its users. Moreover, extract code that applies crop rectangle hardware limits (now a part of .set_selection() operation which is called from set format active processing path) to a new helper and call that helper from set format try processing path as well for symmetry with active. [Sakari Ailus: Rebase on subdev state patches] Fixes: 717fd5b4 ("[media] v4l2: replace try_mbus_fmt by set_fmt") Signed-off-by:Janusz Krzysztofik <jmkrzyszt@gmail.com> Signed-off-by:
Sakari Ailus <sakari.ailus@linux.intel.com> Signed-off-by:
Mauro Carvalho Chehab <mchehab@kernel.org>
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