As the number of phases/taps, used to select the correct equations to compute the ratio, depends on the ratio, start with the 7-tap mode equations to compute an approximation of the ratio, and switch to the 4-tap mode equations if the approximation is lower than or equal to 512. Signed-off-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> --- drivers/media/video/omap3isp/ispresizer.c | 27 ++++++++++++++++++++++----- 1 files changed, 22 insertions(+), 5 deletions(-) diff --git a/drivers/media/video/omap3isp/ispresizer.c b/drivers/media/video/omap3isp/ispresizer.c index 829d7bf..40b2db8 100644 --- a/drivers/media/video/omap3isp/ispresizer.c +++ b/drivers/media/video/omap3isp/ispresizer.c @@ -724,9 +724,20 @@ static void resizer_print_status(struct isp_res_device *res) * vrsz = ((ih - 7) * 256 - 32 - 64 * spv) / (oh - 1) * * The ratios are integer values, and must be rounded down to ensure that the - * cropped input size is not bigger than the uncropped input size. As the ratio - * in 7-tap mode is always smaller than the ratio in 4-tap mode, we can use the - * 7-tap mode equations to compute a ratio approximation. + * cropped input size is not bigger than the uncropped input size. + * + * As the number of phases/taps, used to select the correct equations to compute + * the ratio, depends on the ratio, we start with the 4-tap mode equations to + * compute an approximation of the ratio, and switch to the 7-tap mode equations + * if the approximation is higher than the ratio threshold. + * + * As the 7-tap mode equations will return a ratio smaller than or equal to the + * 4-tap mode equations, the resulting ratio could become lower than or equal to + * the ratio threshold. This 'equations loop' isn't an issue as long as the + * correct equations are used to compute the final input size. Starting with the + * 4-tap mode equations ensure that, in case of values resulting in a 'ratio + * loop', the smallest of the ratio values will be used, never exceeding the + * requested input size. * * We first clamp the output size according to the hardware capabilitie to avoid * auto-cropping the input more than required to satisfy the TRM equations. The @@ -788,8 +799,11 @@ static void resizer_calc_ratios(struct isp_res_device *res, max_height = min_t(unsigned int, max_height, MAX_OUT_HEIGHT); output->height = clamp(output->height, min_height, max_height); - ratio->vert = ((input->height - 7) * 256 - 32 - 64 * spv) + ratio->vert = ((input->height - 4) * 256 - 16 - 32 * spv) / (output->height - 1); + if (ratio->vert > MID_RESIZE_VALUE) + ratio->vert = ((input->height - 7) * 256 - 32 - 64 * spv) + / (output->height - 1); ratio->vert = clamp_t(unsigned int, ratio->vert, MIN_RESIZE_VALUE, MAX_RESIZE_VALUE); @@ -856,8 +870,11 @@ static void resizer_calc_ratios(struct isp_res_device *res, max_width & ~(width_alignment - 1)); output->width = ALIGN(output->width, width_alignment); - ratio->horz = ((input->width - 7) * 256 - 32 - 64 * sph) + ratio->horz = ((input->width - 7) * 256 - 16 - 32 * sph) / (output->width - 1); + if (ratio->horz > MID_RESIZE_VALUE) + ratio->horz = ((input->width - 7) * 256 - 32 - 64 * sph) + / (output->width - 1); ratio->horz = clamp_t(unsigned int, ratio->horz, MIN_RESIZE_VALUE, MAX_RESIZE_VALUE); -- 1.7.3.4 -- 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
