Re: [Xen-devel] [PATCH V1 14/29] xen/video: hdlcd: Use early_printk instead of printk

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 09/06/2013 05:48 PM, Ian Campbell wrote:
> On Wed, 2013-08-28 at 15:47 +0100, Julien Grall wrote:
> > The video driver is initialized before the console is correctly set up.
> > Therefore, printk will never output if there is no serial configured.
> On the flip side if you have a serial console but not early printk you
> won't see these messages instead.
It depends, the console code will parse the console string and 
initialize the different console driver (serial, vga,...) one by one.
  - console=vga,serial => the VGA needs to use early printk
  - console=vga        => the VGA needs to use early printk
  - console=serial,vga => the VGA needs to use printk and can use early 
printk if it's enabled.
> I suppose in that case we don't even try to initialise the hdlcd, since
> it will belong to dom0, right? Except I don't see where that happens.
> Shouldn't this code only be activated if you have console=hdlcd or
> something?
For the moment, the hdlcd is the default device for vga. So if 
console=vga, Xen will initialize the hdcld by calling video_init().
We will need to implement something similar to dt-uart.

> > Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
> > ---
> >   xen/drivers/video/arm_hdlcd.c |   23 ++++++++++++-----------
> >   1 file changed, 12 insertions(+), 11 deletions(-)
> >
> > diff --git a/xen/drivers/video/arm_hdlcd.c b/xen/drivers/video/arm_hdlcd.c
> > index ab464c6..dffda9a 100644
> > --- a/xen/drivers/video/arm_hdlcd.c
> > +++ b/xen/drivers/video/arm_hdlcd.c
> > @@ -146,13 +146,13 @@ void __init video_init(void)
> >
> >       if ( !hdlcd_start )
> >       {
> > -        printk(KERN_ERR "HDLCD address missing from device tree, disabling 
> > driver\n");
> > +        early_printk(KERN_ERR "HDLCD: address missing from device tree, disabling 
> > driver\n");
> >           return;
> >       }
> >
> >       if ( !hdlcd_start || !framebuffer_start )
> >       {
> > -        printk(KERN_ERR "HDLCD: framebuffer address missing from device tree, 
> > disabling driver\n");
> > +        early_printk(KERN_ERR "HDLCD: framebuffer address missing from device tree, 
> > disabling driver\n");
> >           return;
> >       }
> >
> > @@ -166,27 +166,27 @@ void __init video_init(void)
> >       else if ( strlen(mode_string) < strlen("800x600@60") ||
> >               strlen(mode_string) > sizeof(_mode_string) - 1 )
> >       {
> > -        printk(KERN_ERR "HDLCD: invalid modeline=%s\n", mode_string);
> > +        early_printk(KERN_ERR "HDLCD: invalid modeline=%s\n", mode_string);
> >           return;
> >       } else {
> >           char *s = strchr(mode_string, '-');
> >           if ( !s )
> >           {
> > -            printk(KERN_INFO "HDLCD: bpp not found in modeline %s, assume 32 
> > bpp\n",
> > -                    mode_string);
> > +            early_printk(KERN_INFO "HDLCD: bpp not found in modeline %s, assume 32 
> > bpp\n",
> > +                         mode_string);
> >               get_color_masks("32", &c);
> >               memcpy(_mode_string, mode_string, strlen(mode_string) + 1);
> >               bytes_per_pixel = 4;
> >           } else {
> >               if ( strlen(s) < 6 )
> >               {
> > -                printk(KERN_ERR "HDLCD: invalid mode %s\n", mode_string);
> > +                early_printk(KERN_ERR "HDLCD: invalid mode %s\n", mode_string);
> >                   return;
> >               }
> >               s++;
> >               if ( get_color_masks(s, &c) < 0 )
> >               {
> > -                printk(KERN_WARNING "HDLCD: unsupported bpp %s\n", s);
> > +                early_printk(KERN_WARNING "HDLCD: unsupported bpp %s\n", s);
> >                   return;
> >               }
> >               bytes_per_pixel = simple_strtoll(s, NULL, 10) / 8;
> > @@ -205,22 +205,23 @@ void __init video_init(void)
> >       }
> >       if ( !videomode )
> >       {
> > -        printk(KERN_WARNING "HDLCD: unsupported videomode %s\n", _mode_string);
> > +        early_printk(KERN_WARNING "HDLCD: unsupported videomode %s\n",
> > +                     _mode_string);
> >           return;
> >       }
> >
> >       if ( framebuffer_size < bytes_per_pixel * videomode->xres * 
> > videomode->yres )
> >       {
> > -        printk(KERN_ERR "HDLCD: the framebuffer is too small, disabling the HDLCD 
> > driver\n");
> > +        early_printk(KERN_ERR "HDLCD: the framebuffer is too small, disabling the 
> > HDLCD driver\n");
> >           return;
> >       }
> >
> > -    printk(KERN_INFO "Initializing HDLCD driver\n");
> > +    early_printk(KERN_INFO "Initializing HDLCD driver\n");
> >
> >       lfb = ioremap_wc(framebuffer_start, framebuffer_size);
> >       if ( !lfb )
> >       {
> > -        printk(KERN_ERR "Couldn't map the framebuffer\n");
> > +        early_printk(KERN_ERR "Couldn't map the framebuffer\n");
> >           return;
> >       }
> >       memset(lfb, 0x00, bytes_per_pixel * videomode->xres * videomode->yres);

--
Julien Grall

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