linux-kernel - Re: [PATCH v4 7/7] drm/log: Add integer scaling support

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Message-ID: <fab4dac7-e332-452a-8c73-f275c0c76f34@redhat.com>
Date: Fri, 11 Oct 2024 13:58:20 +0200
From: Jocelyn Falempe <jfalempe@...hat.com>
To: Jani Nikula <jani.nikula@...ux.intel.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>,
 John Ogness <john.ogness@...utronix.de>,
 Javier Martinez Canillas <javierm@...hat.com>,
 "Guilherme G . Piccoli" <gpiccoli@...lia.com>,
 bluescreen_avenger@...izon.net, Caleb Connolly <caleb.connolly@...aro.org>,
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 7/7] drm/log: Add integer scaling support

On 11/10/2024 13:18, Jani Nikula wrote:
> On Fri, 11 Oct 2024, Jocelyn Falempe <jfalempe@...hat.com> wrote:
>> Add a module parameter, to increase the font size for HiDPI screen.
>> Even with CONFIG_FONT_TER16x32, it can still be a bit small to read.
>> In this case, adding drm_log.scale=2 to your kernel command line will
>> double the character size.
>>
>> Signed-off-by: Jocelyn Falempe <jfalempe@...hat.com>
>> ---
>>   drivers/gpu/drm/drm_log.c | 27 ++++++++++++++++++---------
>>   1 file changed, 18 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_log.c b/drivers/gpu/drm/drm_log.c
>> index 07d151300146..e44c10819bd0 100644
>> --- a/drivers/gpu/drm/drm_log.c
>> +++ b/drivers/gpu/drm/drm_log.c
>> @@ -25,6 +25,10 @@ MODULE_AUTHOR("Jocelyn Falempe");
>>   MODULE_DESCRIPTION("DRM boot logger");
>>   MODULE_LICENSE("GPL");
>>   
>> +static uint scale = 1;
> 
> Drive-by nit, please use regular types instead of sysv "uint".

ok, you're right. It looks like the most common pattern is to use 
unsigned int for the variable but still call module_param() with uint.
I will fix that for v5.

Thanks,

-- 

Jocelyn
> 
> BR,
> Jani.
> 
>> +module_param(scale, uint, 0444);
>> +MODULE_PARM_DESC(scale, "Integer scaling factor for drm_log, default is 1");
>> +
>>   /**
>>    * DOC: overview
>>    *
>> @@ -38,6 +42,8 @@ struct drm_log_scanout {
>>   	const struct font_desc *font;
>>   	u32 rows;
>>   	u32 columns;
>> +	u32 scaled_font_h;
>> +	u32 scaled_font_w;
>>   	u32 line;
>>   	u32 format;
>>   	u32 px_width;
>> @@ -67,7 +73,7 @@ static struct drm_log *console_to_drm_log(struct console *con)
>>   
>>   static void drm_log_blit(struct iosys_map *dst, unsigned int dst_pitch,
>>   			 const u8 *src, unsigned int src_pitch,
>> -			 u32 height, u32 width, u32 scale, u32 px_width, u32 color)
>> +			 u32 height, u32 width, u32 px_width, u32 color)
>>   {
>>   	switch (px_width) {
>>   	case 2:
>> @@ -87,7 +93,7 @@ static void drm_log_blit(struct iosys_map *dst, unsigned int dst_pitch,
>>   static void drm_log_clear_line(struct drm_log_scanout *scanout, u32 line)
>>   {
>>   	struct drm_framebuffer *fb = scanout->buffer->fb;
>> -	unsigned long height = scanout->font->height;
>> +	unsigned long height = scanout->scaled_font_h;
>>   	struct iosys_map map;
>>   	struct drm_rect r = DRM_RECT_INIT(0, line * height, fb->width, height);
>>   
>> @@ -107,8 +113,8 @@ static void drm_log_draw_line(struct drm_log_scanout *scanout, const char *s,
>>   	size_t font_pitch = DIV_ROUND_UP(font->width, 8);
>>   	const u8 *src;
>>   	u32 px_width = fb->format->cpp[0];
>> -	struct drm_rect r = DRM_RECT_INIT(0, scanout->line * font->height,
>> -					  fb->width, (scanout->line + 1) * font->height);
>> +	struct drm_rect r = DRM_RECT_INIT(0, scanout->line * scanout->scaled_font_h,
>> +					  fb->width, (scanout->line + 1) * scanout->scaled_font_h);
>>   	u32 i;
>>   
>>   	if (drm_client_buffer_vmap_local(scanout->buffer, &map))
>> @@ -118,9 +124,10 @@ static void drm_log_draw_line(struct drm_log_scanout *scanout, const char *s,
>>   	for (i = 0; i < len && i < scanout->columns; i++) {
>>   		u32 color = (i < prefix_len) ? scanout->prefix_color : scanout->front_color;
>>   		src = drm_draw_get_char_bitmap(font, s[i], font_pitch);
>> -		drm_log_blit(&map, fb->pitches[0], src, font_pitch, font->height, font->width,
>> -			     1, px_width, color);
>> -		iosys_map_incr(&map, font->width * px_width);
>> +		drm_log_blit(&map, fb->pitches[0], src, font_pitch,
>> +			     scanout->scaled_font_h, scanout->scaled_font_w,
>> +			     px_width, color);
>> +		iosys_map_incr(&map, scanout->scaled_font_w * px_width);
>>   	}
>>   
>>   	scanout->line++;
>> @@ -205,8 +212,10 @@ static int drm_log_setup_modeset(struct drm_client_dev *client,
>>   		return -ENOMEM;
>>   	}
>>   	mode_set->fb = scanout->buffer->fb;
>> -	scanout->rows = height / scanout->font->height;
>> -	scanout->columns = width / scanout->font->width;
>> +	scanout->scaled_font_h = scanout->font->height * scale;
>> +	scanout->scaled_font_w = scanout->font->width * scale;
>> +	scanout->rows = height / scanout->scaled_font_h;
>> +	scanout->columns = width / scanout->scaled_font_w;
>>   	scanout->front_color = drm_draw_color_from_xrgb8888(0xffffff, format);
>>   	scanout->prefix_color = drm_draw_color_from_xrgb8888(0x4e9a06, format);
>>   	return 0;
>