[PATCH] neofb: avoid resetting display config on unblank (v2)

There were two mistakes in the register-read-on-(un)blank approach.

- First, without proper register (un)locking the value read back will always
  be zero, and this is what I missed entirely until just now.  Due to this,
  the logic could not be verified at all and I tried some bogus checks which
  are completely stupid.

- Second, the LCD status bit will always be set to zero when the backlight
  has been turned off.  Reading the value back during unblank will disable the
  LCD unconditionally, regardless of the state it is supposed to be in, since
  we set it to zero beforehand.

So this is what we do now:

- create a new variable in struct neofb_par, and use that to determine
  whether to read back registers (initialized to true)

- before actually blanking the screen, read back the register to sense any
  possible change made through Fn key combo

- use proper neoUnlock() / neoLock() to actually read something

- every call to neofb_blank() determines if we read back next time: blanking
  disables readback, unblanking (FB_BLANK_UNBLANK) enables it

This should give us a nice and clean state machine.  Has been thoroughly
tested on a Dell Latitude CPiA / NM220 Chip docked to a C/Dock2 with attached
CRT in all possible combinations of LCD/CRT on/off.  I changed the config via
Fn key, let the console blank, unblanked by keypress - works flawlessly.

Signed-off-by: Christian Trefzer <ctrefzer@gmx.de>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/drivers/video/neofb.c b/drivers/video/neofb.c
index b85e2b180a4488f9eeeb99d69d7dedf7c1c7f9b0..a2e201dc40f774a57976d1b41201cfb9aa574031 100644 (file)
--- a/drivers/video/neofb.c
+++ b/drivers/video/neofb.c
@@ -843,6 +843,9 @@ static int neofb_set_par(struct fb_info *info)
 
        par->SysIfaceCntl2 = 0xc0;      /* VESA Bios sets this to 0x80! */
 
+       /* Initialize: by default, we want display config register to be read */
+       par->PanelDispCntlRegRead = 1;
+
        /* Enable any user specified display devices. */
        par->PanelDispCntlReg1 = 0x00;
        if (par->internal_display)
@@ -1334,11 +1337,17 @@ static int neofb_blank(int blank_mode, struct fb_info *info)
        struct neofb_par *par = info->par;
        int seqflags, lcdflags, dpmsflags, reg;
 
+
        /*
-        * Reload the value stored in the register, might have been changed via
-        * FN keystroke
+        * Reload the value stored in the register, if sensible. It might have
+        * been changed via FN keystroke.
         */
-       par->PanelDispCntlReg1 = vga_rgfx(NULL, 0x20) & 0x03;
+       if (par->PanelDispCntlRegRead) {
+               neoUnlock();
+               par->PanelDispCntlReg1 = vga_rgfx(NULL, 0x20) & 0x03;
+               neoLock(&par->state);
+       }
+       par->PanelDispCntlRegRead = !blank_mode;
 
        switch (blank_mode) {
        case FB_BLANK_POWERDOWN:        /* powerdown - both sync lines down */

diff --git a/include/video/neomagic.h b/include/video/neomagic.h
index 1d69049bd4c196ee13ab3e7a6439d20d5cf47008..78b1f15a538fc69a0aaf2f94c11a400d5ad2193d 100644 (file)
--- a/include/video/neomagic.h
+++ b/include/video/neomagic.h
@@ -159,6 +159,7 @@ struct neofb_par {
        unsigned char PanelDispCntlReg1;
        unsigned char PanelDispCntlReg2;
        unsigned char PanelDispCntlReg3;
+       unsigned char PanelDispCntlRegRead;
        unsigned char PanelVertCenterReg1;
        unsigned char PanelVertCenterReg2;
        unsigned char PanelVertCenterReg3;