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

[Julien Grall <julien.grall@linaro.org>]

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@linaro.org>
>> ---
>>   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