----- Mail Original ----- De: "Trent Piepho" <xyzzy@xxxxxxxxxxxxx> À: "robert jarzmik" <robert.jarzmik@xxxxxxx> Cc: "Guennadi Liakhovetski" <g.liakhovetski@xxxxxx>, mike@xxxxxxxxxxxxxx, "Linux Media Mailing List" <linux-media@xxxxxxxxxxxxxxx> Envoyé: Vendredi 6 Mars 2009 10h56:39 GMT +01:00 Amsterdam / Berlin / Berne / Rome / Stockholm / Vienne Objet: Re: [PATCH 1/4] pxa_camera: Remove YUV planar formats hole > I remade my calculations : > - if (width x height % 8 == 0) : > => frame size = width x height x 2 > => U plane size = frame size / 4 = width x height /2 > => U plane size is a multiple of 4 > As the last DMA load from QIF fifo will return 8 bytes (and not 4 as > we would expect, cf. PXA Developer's Manual, 27.4.4.1), this is not > good. So it's only a requirement that the total size of all three planes put together is a multiple of 8? Or is it a requirement that each plane is a multiple of 8? And are you using 4:2:2 or 4:2:0? The requirement is for each plane, as each plane has a QIF fifo associated. If the requirement is granted for plane U, then it is for plane V (same size), and plane Y as well (twice the size of plane U). And the file format is planar 4:2:2 YCbCr, which gives (assuming 32 bit wide representation, with most significant bit on the left of the schema and least on the right) for example : 31 23 15 7 0 +------+------+------+------+ | Yn+3 | Yn+2 | Yn+1 | Yn | | ..........................| + YN | YN-1 | YN-1 | 0 | +------+------+------+------+ | Cr+3 | Cr+2 | Cr+1 | Cr | | ..........................| | CrN | CrN-1| 0 | 0 | +------+------+------+------+ | Cr+3 | Cr+2 | Cr+1 | Cr | | ..........................| | CrN | CrN-1| 0 | 0 | +------+------+------+------+ Everywhere where I put a "0", de QIF interface sends a 0 byte even if it doesn't represent a pixel (padding by 0s). The same is true for RGB formats, but instead of 0, it is 0 or "transparency bit". For the height/width calculation, I didn't find your function in kernel tree. As it is very generic, I have no way to put it into pxa_camera, it should go ... elsewhere. So I think I'll use a dumb "ALIGN(x, 8)" ... Cheers. -- Robert -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
