From: Nicolas Ferre Manage atmel_lcdfb FIFO underflow rework Resetting the LCD and DMA allows to fix screen shifting after a FIFO underflow. It follows reset sequence from errata "LCD Screen Shifting After a Reset". Reworked following Andrew Morton comments. Signed-off-by: Nicolas Ferre Cc: Haavard Skinnemoen Cc: Andrew Victor Signed-off-by: Andrew Morton --- drivers/video/atmel_lcdfb.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff -puN drivers/video/atmel_lcdfb.c~atmel_lcdfb-fifo-underflow-management-rework drivers/video/atmel_lcdfb.c --- a/drivers/video/atmel_lcdfb.c~atmel_lcdfb-fifo-underflow-management-rework +++ a/drivers/video/atmel_lcdfb.c @@ -384,6 +384,8 @@ static int atmel_lcdfb_check_var(struct */ static void atmel_lcdfb_reset(struct atmel_lcdfb_info *sinfo) { + might_sleep(); + /* LCD power off */ lcdc_writel(sinfo, ATMEL_LCDC_PWRCON, sinfo->guard_time << ATMEL_LCDC_GUARDT_OFFSET); @@ -428,6 +430,8 @@ static int atmel_lcdfb_set_par(struct fb unsigned long clk_value_khz; unsigned long bits_per_line; + might_sleep(); + dev_dbg(info->device, "%s:\n", __func__); dev_dbg(info->device, " * resolution: %ux%u (%ux%u virtual)\n", info->var.xres, info->var.yres, @@ -869,7 +873,8 @@ static int __init atmel_lcdfb_probe(stru goto unmap_mmio; } - /* Initialize bottom half workqueue */ + /* Some operations on the LCDC might sleep and + * require a preemptible task context */ INIT_WORK(&sinfo->task, atmel_lcdfb_task); ret = atmel_lcdfb_init_fbinfo(sinfo); @@ -914,6 +919,7 @@ static int __init atmel_lcdfb_probe(stru free_cmap: fb_dealloc_cmap(&info->cmap); unregister_irqs: + cancel_work_sync(&sinfo->task); free_irq(sinfo->irq_base, info); unmap_mmio: exit_backlight(sinfo); @@ -951,6 +957,7 @@ static int __exit atmel_lcdfb_remove(str if (!sinfo) return 0; + cancel_work_sync(&sinfo->task); exit_backlight(sinfo); if (sinfo->atmel_lcdfb_power_control) sinfo->atmel_lcdfb_power_control(0); _