Re: [PATCH] drm/udl: Fix for the X server screen update

[poma <pomidorabelisima@gmail.com>]

On 18.09.2016 19:42, Noralf Trønnes wrote:
> 
> Den 18.09.2016 15:48, skrev poma:
>> Fix for DisplayLink GPU USB2.0 device X server screen update
>>
>> Within X server on top of DisplayLink GPU USB2.0 device,
>> screen content is not refreshed i.e. updated,
>> which is the most basic functionality of the screen.
>>
>> This partially (udl_handle_damage()) reverts commit:
>>
>> - e375882406d0cc24030746638592004755ed4ae0
>>    "drm/udl: Use drm_fb_helper deferred_io support"
>>
>> Thanks Noralf for the tip.
>>
>> $ modinfo udl
>> filename:       /lib/modules/4.7.4-234.fc24.x86_64/updates/udl.ko
>> license:        GPL
>> alias:          usb:v17E9p*d*dc*dsc*dp*icFFisc00ip00in*
>> depends:
>> intree:         Y
>> vermagic:       4.7.4-234.fc24.x86_64 SMP mod_unload
>> parm:           fb_bpp:int
>> parm:           fb_defio:int
>>
>> $ dmesg | grep udl
>> [   41.888469] udl: module verification failed: signature and/or required key missing - tainting kernel
>> [   42.156988] udl 1-2:1.0: fb1: udldrmfb frame buffer device
>> [   42.158940] [drm] Initialized udl on minor 1
>> [   42.159676] usbcore: registered new interface driver udl
>>
>> $ grep udl /var/log/Xorg.0.log
>> [    71.194] (**) |   |-->Device "udl0"
>>
>> Tested-by: poma <poma@gmail.com>
>> ---
>>   drivers/gpu/drm/udl/udl_drv.h |  2 ++
>>   drivers/gpu/drm/udl/udl_fb.c  | 39 +++++++++++++++++++++++++++++++++++++--
>>   2 files changed, 39 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/udl/udl_drv.h b/drivers/gpu/drm/udl/udl_drv.h
>> index 0b03d34..4a064ef 100644
>> --- a/drivers/gpu/drm/udl/udl_drv.h
>> +++ b/drivers/gpu/drm/udl/udl_drv.h
>> @@ -81,6 +81,8 @@ struct udl_framebuffer {
>>   	struct drm_framebuffer base;
>>   	struct udl_gem_object *obj;
>>   	bool active_16; /* active on the 16-bit channel */
>> +	int x1, y1, x2, y2; /* dirty rect */
>> +	spinlock_t dirty_lock;
>>   };
>>   
>>   #define to_udl_fb(x) container_of(x, struct udl_framebuffer, base)
>> diff --git a/drivers/gpu/drm/udl/udl_fb.c b/drivers/gpu/drm/udl/udl_fb.c
>> index d5df555..b2b42d2 100644
>> --- a/drivers/gpu/drm/udl/udl_fb.c
>> +++ b/drivers/gpu/drm/udl/udl_fb.c
>> @@ -90,6 +90,9 @@ int udl_handle_damage(struct udl_framebuffer *fb, int x, int y,
>>   	struct urb *urb;
>>   	int aligned_x;
>>   	int bpp = (fb->base.bits_per_pixel / 8);
>> +	int x2, y2;
>> +	bool store_for_later = false;
>> +	unsigned long flags;
>>   
>>   	if (!fb->active_16)
>>   		return 0;
>> @@ -115,6 +118,38 @@ int udl_handle_damage(struct udl_framebuffer *fb, int x, int y,
>>   	    (y + height > fb->base.height))
>>   		return -EINVAL;
>>   
>> +	/* if we are in atomic just store the info
>> +	   can't test inside spin lock */
>> +	if (in_atomic())
>> +		store_for_later = true;
>> +
>> +	x2 = x + width - 1;
>> +	y2 = y + height - 1;
>> +
>> +	spin_lock_irqsave(&fb->dirty_lock, flags);
> 
> You can drop the spinlock and store_for_later since it always runs in
> process context.
> Which means that there's no need to store x1/x2/y1/y2 in fb.
> 
>> +
>> +	if (fb->y1 < y)
>> +		y = fb->y1;
>> +	if (fb->y2 > y2)
>> +		y2 = fb->y2;
>> +	if (fb->x1 < x)
>> +		x = fb->x1;
>> +	if (fb->x2 > x2)
>> +		x2 = fb->x2;
>> +
>> +	if (store_for_later) {
>> +		fb->x1 = x;
>> +		fb->x2 = x2;
>> +		fb->y1 = y;
>> +		fb->y2 = y2;
>> +		spin_unlock_irqrestore(&fb->dirty_lock, flags);
>> +		return 0;
>> +	}
>> +
>> +	fb->x1 = fb->y1 = INT_MAX;
>> +	fb->x2 = fb->y2 = 0;
>> +
>> +	spin_unlock_irqrestore(&fb->dirty_lock, flags);
>>   	start_cycles = get_cycles();
>>   
>>   	urb = udl_get_urb(dev);
>> @@ -122,14 +157,14 @@ int udl_handle_damage(struct udl_framebuffer *fb, int x, int y,
>>   		return 0;
>>   	cmd = urb->transfer_buffer;
>>   
>> -	for (i = y; i < height ; i++) {
>> +	for (i = y; i <= y2 ; i++) {
>>   		const int line_offset = fb->base.pitches[0] * i;
>>   		const int byte_offset = line_offset + (x * bpp);
>>   		const int dev_byte_offset = (fb->base.width * bpp * i) + (x * bpp);
>>   		if (udl_render_hline(dev, bpp, &urb,
>>   				     (char *) fb->obj->vmapping,
>>   				     &cmd, byte_offset, dev_byte_offset,
>> -				     width * bpp,
> 

That's right, this is sufficient

---
 drivers/gpu/drm/udl/udl_fb.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/udl/udl_fb.c b/drivers/gpu/drm/udl/udl_fb.c
index d5df555..05ab114 100644
--- a/drivers/gpu/drm/udl/udl_fb.c
+++ b/drivers/gpu/drm/udl/udl_fb.c
@@ -90,6 +90,7 @@ int udl_handle_damage(struct udl_framebuffer *fb, int x, int y,
 	struct urb *urb;
 	int aligned_x;
 	int bpp = (fb->base.bits_per_pixel / 8);
+	int x2, y2;
 
 	if (!fb->active_16)
 		return 0;
@@ -115,6 +116,9 @@ int udl_handle_damage(struct udl_framebuffer *fb, int x, int y,
 	    (y + height > fb->base.height))
 		return -EINVAL;
 
+	x2 = x + width - 1;
+	y2 = y + height - 1;
+
 	start_cycles = get_cycles();
 
 	urb = udl_get_urb(dev);
@@ -122,14 +126,14 @@ int udl_handle_damage(struct udl_framebuffer *fb, int x, int y,
 		return 0;
 	cmd = urb->transfer_buffer;
 
-	for (i = y; i < height ; i++) {
+	for (i = y; i <= y2 ; i++) {
 		const int line_offset = fb->base.pitches[0] * i;
 		const int byte_offset = line_offset + (x * bpp);
 		const int dev_byte_offset = (fb->base.width * bpp * i) + (x * bpp);
 		if (udl_render_hline(dev, bpp, &urb,
 				     (char *) fb->obj->vmapping,
 				     &cmd, byte_offset, dev_byte_offset,
-				     width * bpp,
+				     (x2 - x + 1) * bpp,
 				     &bytes_identical, &bytes_sent))
 			goto error;
 	}
-- 

> There is obviously something wrong with the use of height/width here
> as a substitute for y2 and the x1 formula.
> If you add a printk here you can see how they differ.
> 
> Noralf.
> 
>> +				     (x2 - x + 1) * bpp,
>>   				     &bytes_identical, &bytes_sent))
>>   			goto error;
>>   	}
> 

What exact kernel print expression and where to insert it?
By following instructions: http://elinux.org/Debugging_by_printing
printk content doesn't shows within dmesg output.


_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel