linux-kernel - [PATCH 4/7] dmaengine: at_xdmac: restore the content of grws register

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Message-ID: <20230214151827.1050280-5-claudiu.beznea@microchip.com>
Date:   Tue, 14 Feb 2023 17:18:24 +0200
From:   Claudiu Beznea <claudiu.beznea@...rochip.com>
To:     <ludovic.desroches@...rochip.com>, <tudor.ambarus@...aro.org>,
        <vkoul@...nel.org>, <nicolas.ferre@...rochip.com>
CC:     <linux-arm-kernel@...ts.infradead.org>,
        <dmaengine@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Claudiu Beznea <claudiu.beznea@...rochip.com>
Subject: [PATCH 4/7] dmaengine: at_xdmac: restore the content of grws register

In case the system suspends to a deep sleep state where power to DMA
controller is cut-off we need to restore the content of GRWS register.
This is a write only register and writing bit X tells the controller
to suspend read and write requests for channel X. Thus set GRWS before
restoring the content of GE (Global Enable) regiter.

Fixes: e1f7c9eee707 ("dmaengine: at_xdmac: creation of the atmel eXtended DMA Controller driver")
Signed-off-by: Claudiu Beznea <claudiu.beznea@...rochip.com>
---
 drivers/dma/at_xdmac.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c
index fa1e2e0da02f..34c004a4b23c 100644
--- a/drivers/dma/at_xdmac.c
+++ b/drivers/dma/at_xdmac.c
@@ -2211,6 +2211,15 @@ static int __maybe_unused atmel_xdmac_resume(struct device *dev)
 					return ret;
 				at_xdmac_device_resume_internal(atchan);
 			}
+
+			/*
+			 * We may resume from a deep sleep state where power
+			 * to DMA controller is cut-off. Thus, restore the
+			 * suspend state of channels set though dmaengine API.
+			 */
+			else if (at_xdmac_chan_is_paused(atchan))
+				at_xdmac_device_pause_set(atxdmac, atchan);
+
 			at_xdmac_chan_write(atchan, AT_XDMAC_CNDA, atchan->save_cnda);
 			at_xdmac_chan_write(atchan, AT_XDMAC_CNDC, atchan->save_cndc);
 			at_xdmac_chan_write(atchan, AT_XDMAC_CIE, atchan->save_cim);
-- 
2.34.1