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fbdev: Distinguish between interlaced and progressive modes
authorFredrik Noring <noring@nocrew.org>
Tue, 24 Jul 2018 17:11:24 +0000 (19:11 +0200)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 26 Sep 2018 06:39:25 +0000 (08:39 +0200)
commit8c448f47bf018c5eaa06bb3b4805190387898db2
treed1aed65833d479639f783eb5e29348279f416fc6
parent8fc18a9186d1f1b4fa0e3d6901b1db9e090cee41
fbdev: Distinguish between interlaced and progressive modes

[ Upstream commit 1ba0a59cea41ea05fda92daaf2a2958a2246b9cf ]

I discovered the problem when developing a frame buffer driver for the
PlayStation 2 (not yet merged), using the following video modes for the
PlayStation 3 in drivers/video/fbdev/ps3fb.c:

    }, {
        /* 1080if */
        "1080if", 50, 1920, 1080, 13468, 148, 484, 36, 4, 88, 5,
        FB_SYNC_BROADCAST, FB_VMODE_INTERLACED
    }, {
        /* 1080pf */
        "1080pf", 50, 1920, 1080, 6734, 148, 484, 36, 4, 88, 5,
        FB_SYNC_BROADCAST, FB_VMODE_NONINTERLACED
    },

In ps3fb_probe, the mode_option module parameter is used with fb_find_mode
but it can only select the interlaced variant of 1920x1080 since the loop
matching the modes does not take the difference between interlaced and
progressive modes into account.

In short, without the patch, progressive 1920x1080 cannot be chosen as a
mode_option parameter since fb_find_mode (falsely) thinks interlace is a
perfect match.

Signed-off-by: Fredrik Noring <noring@nocrew.org>
Cc: "Maciej W. Rozycki" <macro@linux-mips.org>
[b.zolnierkie: updated patch description]
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/video/fbdev/core/modedb.c