From: Wolfram Sang <wsa+renesas@sang-engineering.com>
To: linux-i2c@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, linux-renesas-soc@vger.kernel.org,
linux-iio@vger.kernel.org, linux-input@vger.kernel.org,
linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org,
Wolfram Sang <wsa+renesas@sang-engineering.com>
Subject: [RFC PATCH v5 5/6] i2c: rcar: skip DMA if buffer is not safe
Date: Wed, 20 Sep 2017 20:59:55 +0200 [thread overview]
Message-ID: <20170920185956.13874-6-wsa+renesas@sang-engineering.com> (raw)
In-Reply-To: <20170920185956.13874-1-wsa+renesas@sang-engineering.com>
This HW is prone to races, so it needs to setup new messages in irq
context. That means we can't alloc bounce buffers if a message buffer is
not DMA safe. So, in that case, simply fall back to PIO.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---
drivers/i2c/busses/i2c-rcar.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c
index 15d764afec3b29..8a2ae3e6c561c4 100644
--- a/drivers/i2c/busses/i2c-rcar.c
+++ b/drivers/i2c/busses/i2c-rcar.c
@@ -359,7 +359,7 @@ static void rcar_i2c_dma(struct rcar_i2c_priv *priv)
int len;
/* Do not use DMA if it's not available or for messages < 8 bytes */
- if (IS_ERR(chan) || msg->len < 8)
+ if (IS_ERR(chan) || msg->len < 8 || !(msg->flags & I2C_M_DMA_SAFE))
return;
if (read) {
--
2.11.0
next prev parent reply other threads:[~2017-09-20 18:59 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-20 18:59 [RFC PATCH v5 0/6] i2c: document DMA handling and add helpers for it Wolfram Sang
2017-09-20 18:59 ` [RFC PATCH v5 1/6] i2c: add a message flag for DMA safe buffers Wolfram Sang
2017-09-20 18:59 ` [RFC PATCH v5 2/6] i2c: add helpers to ease DMA handling Wolfram Sang
2017-09-21 13:59 ` Jonathan Cameron
[not found] ` <20170921145922.000017b5-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
2017-09-21 14:05 ` Jonathan Cameron
2017-09-21 14:15 ` Wolfram Sang
2017-09-21 14:36 ` Jonathan Cameron
2017-09-20 18:59 ` [RFC PATCH v5 3/6] i2c: add docs to clarify " Wolfram Sang
2017-09-20 19:56 ` Mauro Carvalho Chehab
2017-09-21 14:08 ` Jonathan Cameron
2017-09-20 18:59 ` [RFC PATCH v5 4/6] i2c: sh_mobile: use helper to decide if DMA is useful Wolfram Sang
2017-09-20 18:59 ` Wolfram Sang [this message]
2017-09-20 18:59 ` [RFC PATCH v5 6/6] i2c: dev: mark RDWR buffers as DMA_SAFE Wolfram Sang
2017-09-21 14:17 ` Jonathan Cameron
2017-09-21 14:23 ` Wolfram Sang
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