fbtft: Flush any deferred updates on release #5463
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Since [1], writing to the fbtft framebuffer and immediately closing the file descriptor is likely to have no effect. This is because the framebuffer deferred IO framework is now careful to cancel pending updates. To retain the old behaviour, add an fb_release method that flushes the updates instead. [1] 3efc61d ("fbdev: Fix invalid page access after closing deferred I/O devices")
Contributor
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You're submitting a minor tweak on my PR (#5399) but without mentioning the fact in the PR? I guess the See: counts. If you'd read around a bit more you'd find that I submitted an alternative workaround (#5413) that should work for all drivers using fb_deferred_io without causing slow-down for user-space code that rapidly opens and closes the device. |
Author
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Thanks for pointing me that direction, must have missed your alternative workaround. Unfortunately #5413 does not work in my case. Writing to the framebuffer and closing the file descriptor immediately does not have any effect. |
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Since [1], writing to the fbtft framebuffer and immediately closing the file descriptor is likely to have no effect. This is because the framebuffer deferred IO framework is now careful to cancel pending updates.
To retain the old behaviour, add an fb_release method that flushes the updates instead.
See: #5399
[1] 3efc61d ("fbdev: Fix invalid page access after closing #deferred I/O devices")