LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Robin Gong <b38343@freescale.com>
To: <dan.j.williams@intel.com>, <vinod.koul@intel.com>
Cc: <dmaengine@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: [PATCH v4] dma: imx-sdma: switch to dynamic context mode after script loaded
Date: Sun, 15 Feb 2015 10:00:35 +0800	[thread overview]
Message-ID: <1423965635-13915-1-git-send-email-b38343@freescale.com> (raw)

Below comments got from Page4724 of Reference Manual of i.mx6q:
http://cache.freescale.com/files/32bit/doc/ref_manual/IMX6DQRM.pdf

--"Static context mode should be used for the first channel called
after reset to ensure that the all context RAM for that channel is
initialized during the context SAVE phase when the channel is
done or yields. Subsequent calls to the same channel or
different channels may use any of the dynamic context modes.
This will ensure that all context locations for the bootload
channel are initialized, and prevent undefined values in context
RAM from being loaded during the context restore if the
channel is re-started later"

Unfortunately, the rule was broken by commit(5b28aa319bba96987316425a1131813d87cbab35)
.This patch just take them back.

Signed-off-by: Robin Gong <b38343@freescale.com>
---
 drivers/dma/imx-sdma.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
index d0df198..644cfa0 100644
--- a/drivers/dma/imx-sdma.c
+++ b/drivers/dma/imx-sdma.c
@@ -531,6 +531,10 @@ static int sdma_run_channel0(struct sdma_engine *sdma)
 		dev_err(sdma->dev, "Timeout waiting for CH0 ready\n");
 	}
 
+	/* Set bits of CONFIG register with dynamic context switching */
+	if (readl(sdma->regs + SDMA_H_CONFIG) == 0)
+		writel_relaxed(SDMA_H_CONFIG_CSM, sdma->regs + SDMA_H_CONFIG);
+
 	return ret ? 0 : -ETIMEDOUT;
 }
 
@@ -1401,9 +1405,6 @@ static int sdma_init(struct sdma_engine *sdma)
 
 	writel_relaxed(ccb_phys, sdma->regs + SDMA_H_C0PTR);
 
-	/* Set bits of CONFIG register with given context switching mode */
-	writel_relaxed(SDMA_H_CONFIG_CSM, sdma->regs + SDMA_H_CONFIG);
-
 	/* Initializes channel's priorities */
 	sdma_set_channel_priority(&sdma->channel[0], 7);
 
-- 
1.9.1


             reply	other threads:[~2015-02-15  3:12 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-02-15  2:00 Robin Gong [this message]
2015-03-16 10:25 ` Vinod Koul

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1423965635-13915-1-git-send-email-b38343@freescale.com \
    --to=b38343@freescale.com \
    --cc=dan.j.williams@intel.com \
    --cc=dmaengine@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=vinod.koul@intel.com \
    --subject='Re: [PATCH v4] dma: imx-sdma: switch to dynamic context mode after script loaded' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).