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authorEd Blake <ed.blake@sondrel.com>2017-10-09 15:40:26 +0100
committerVinod Koul <vinod.koul@intel.com>2017-10-16 12:15:30 +0530
commitfd9f22ae15b97997c76cdadf2bed23053881509a (patch)
tree0c3a0267897e3136dc5e25d314996050ddf39b96 /drivers
parent2bd6bf03f4c1c59381d62c61d03f6cc3fe71f66e (diff)
dmaengine: img-mdc: Add suspend / resume handling
Add suspend / resume handling using suspend_late and resume_early, and check that all channels are idle before suspending. DMA drivers should use suspend_late / resume_early to ensure that all DMA client devices are suspended before the DMA device itself, and that client devices are resumed after the DMA device. This avoids suspending the DMA device while transactions are still active. It is the responsibility of client drivers to terminate all DMA transactions in their suspend handlers, so there should be no active transactions by the time suspend_late is called. There's no need to save and restore registers for MDC during suspend / resume, as all transactions will be terminated as a result of the suspend, and all required registers are programmed anyway at the start of any new transactions following resume. Signed-off-by: Ed Blake <ed.blake@sondrel.com> Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/dma/img-mdc-dma.c33
1 files changed, 33 insertions, 0 deletions
diff --git a/drivers/dma/img-mdc-dma.c b/drivers/dma/img-mdc-dma.c
index 54db1411ce73..c4d8d5ad2876 100644
--- a/drivers/dma/img-mdc-dma.c
+++ b/drivers/dma/img-mdc-dma.c
@@ -1009,9 +1009,42 @@ static int mdc_dma_remove(struct platform_device *pdev)
return 0;
}
+#ifdef CONFIG_PM_SLEEP
+static int img_mdc_suspend_late(struct device *dev)
+{
+ struct mdc_dma *mdma = dev_get_drvdata(dev);
+ int i;
+
+ /* Check that all channels are idle */
+ for (i = 0; i < mdma->nr_channels; i++) {
+ struct mdc_chan *mchan = &mdma->channels[i];
+
+ if (unlikely(mchan->desc))
+ return -EBUSY;
+ }
+
+ clk_disable_unprepare(mdma->clk);
+
+ return 0;
+}
+
+static int img_mdc_resume_early(struct device *dev)
+{
+ struct mdc_dma *mdma = dev_get_drvdata(dev);
+
+ return clk_prepare_enable(mdma->clk);
+}
+#endif /* CONFIG_PM_SLEEP */
+
+static const struct dev_pm_ops img_mdc_pm_ops = {
+ SET_LATE_SYSTEM_SLEEP_PM_OPS(img_mdc_suspend_late,
+ img_mdc_resume_early)
+};
+
static struct platform_driver mdc_dma_driver = {
.driver = {
.name = "img-mdc-dma",
+ .pm = &img_mdc_pm_ops,
.of_match_table = of_match_ptr(mdc_dma_of_match),
},
.probe = mdc_dma_probe,