linux-kernel - [PATCH 10/10] [RFC] video: fbdev: atari: Remove backward bug-compatibility

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Message-Id: <52d52566a80bfd00acdcfc28a24799d3fbf638f6.1657554353.git.geert@linux-m68k.org>
Date:   Mon, 11 Jul 2022 17:50:34 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Helge Deller <deller@....de>
Cc:     Michael Schmitz <schmitzmic@...il.com>,
        Jonathan Corbet <corbet@....net>, linux-fbdev@...r.kernel.org,
        linux-doc@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-m68k@...r.kernel.org, linux-kernel@...r.kernel.org,
        Geert Uytterhoeven <geert@...ux-m68k.org>
Subject: [PATCH 10/10] [RFC] video: fbdev: atari: Remove backward bug-compatibility

As of v2.1.0, falcon_decode_var() contains a quirk to fix a rounding
error, as explained by Günther Kelleter on Fri, 30 Aug 1996:

    This diff removes the now obsolete Falcon video option "pwrsave", and
    fixes a rounding error that is triggered by the resolution switching X
    server (those who use the pixel clock value 39722 in their /etc/fb.modes
    should change it to 39721).

However, this causes the modified video mode returned by
falcon_decode_var() to not match the video mode returned by
falcon_encode_var().  Fix this by dropping the quirk.

Unfortunately /etc/fb.modes in fbset was never updated, so the
"640x480-60" mode still contains the wrong pixclock.
Hence this change may introduce a regression.

Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>
---
Any comments?
---
 drivers/video/fbdev/atafb.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/drivers/video/fbdev/atafb.c b/drivers/video/fbdev/atafb.c
index e8b178e732e2c785..2bc4089865e60ac2 100644
--- a/drivers/video/fbdev/atafb.c
+++ b/drivers/video/fbdev/atafb.c
@@ -1008,10 +1008,6 @@ static int falcon_decode_var(struct fb_var_screeninfo *var,
 	else if (yres_virtual < yres)
 		yres_virtual = yres;
 
-	/* backward bug-compatibility */
-	if (var->pixclock > 1)
-		var->pixclock -= 1;
-
 	par->hw.falcon.line_width = bpp * xres / 16;
 	par->hw.falcon.line_offset = bpp * (xres_virtual - xres) / 16;
 
-- 
2.25.1