diff options
Diffstat (limited to 'drivers/video')
| -rw-r--r-- | drivers/video/sh_mobile_lcdcfb.c | 32 |
1 files changed, 24 insertions, 8 deletions
diff --git a/drivers/video/sh_mobile_lcdcfb.c b/drivers/video/sh_mobile_lcdcfb.c index 3ad5157f989..b4b5de930cf 100644 --- a/drivers/video/sh_mobile_lcdcfb.c +++ b/drivers/video/sh_mobile_lcdcfb.c @@ -281,18 +281,34 @@ static void sh_mobile_lcdc_deferred_io(struct fb_info *info, struct list_head *pagelist) { struct sh_mobile_lcdc_chan *ch = info->par; - unsigned int nr_pages; /* enable clocks before accessing hardware */ sh_mobile_lcdc_clk_on(ch->lcdc); - nr_pages = sh_mobile_lcdc_sginit(info, pagelist); - dma_map_sg(info->dev, ch->sglist, nr_pages, DMA_TO_DEVICE); - - /* trigger panel update */ - lcdc_write_chan(ch, LDSM2R, 1); - - dma_unmap_sg(info->dev, ch->sglist, nr_pages, DMA_TO_DEVICE); + /* + * It's possible to get here without anything on the pagelist via + * sh_mobile_lcdc_deferred_io_touch() or via a userspace fsync() + * invocation. In the former case, the acceleration routines are + * stepped in to when using the framebuffer console causing the + * workqueue to be scheduled without any dirty pages on the list. + * + * Despite this, a panel update is still needed given that the + * acceleration routines have their own methods for writing in + * that still need to be updated. + * + * The fsync() and empty pagelist case could be optimized for, + * but we don't bother, as any application exhibiting such + * behaviour is fundamentally broken anyways. + */ + if (!list_empty(pagelist)) { + unsigned int nr_pages = sh_mobile_lcdc_sginit(info, pagelist); + + /* trigger panel update */ + dma_map_sg(info->dev, ch->sglist, nr_pages, DMA_TO_DEVICE); + lcdc_write_chan(ch, LDSM2R, 1); + dma_unmap_sg(info->dev, ch->sglist, nr_pages, DMA_TO_DEVICE); + } else + lcdc_write_chan(ch, LDSM2R, 1); } static void sh_mobile_lcdc_deferred_io_touch(struct fb_info *info) |