From: Paul Cercueil <paul@crapouillou.net>
To: Ulf Hansson <ulf.hansson@linaro.org>, Rob Herring <robh+dt@kernel.org>
Cc: list@opendingux.net, linux-mmc@vger.kernel.org,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mips@vger.kernel.org, Paul Cercueil <paul@crapouillou.net>
Subject: [PATCH 2/2] mmc: jz4740: Support using a bi-directional DMA channel
Date: Mon, 20 Dec 2021 19:08:40 +0000 [thread overview]
Message-ID: <20211220190840.108061-3-paul@crapouillou.net> (raw)
In-Reply-To: <20211220190840.108061-1-paul@crapouillou.net>
Since the MMC/SD controller in Ingenic SoCs work in half-duplex, it is
possible to use one single DMA channel for both TX and RX operations,
instead of using separate channels.
As some older Ingenic SoCs offer only a handful of DMA channels,
supporting bi-directional channels allow more hardware to use the
channels that would otherwise be used for the MMC/SD operation.
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
---
drivers/mmc/host/jz4740_mmc.c | 19 +++++++++++++++++--
1 file changed, 17 insertions(+), 2 deletions(-)
diff --git a/drivers/mmc/host/jz4740_mmc.c b/drivers/mmc/host/jz4740_mmc.c
index 80a2c270d502..a0b94f61ddcf 100644
--- a/drivers/mmc/host/jz4740_mmc.c
+++ b/drivers/mmc/host/jz4740_mmc.c
@@ -217,11 +217,23 @@ static void jz4740_mmc_release_dma_channels(struct jz4740_mmc_host *host)
return;
dma_release_channel(host->dma_tx);
- dma_release_channel(host->dma_rx);
+ if (host->dma_rx)
+ dma_release_channel(host->dma_rx);
}
static int jz4740_mmc_acquire_dma_channels(struct jz4740_mmc_host *host)
{
+ struct device *dev = mmc_dev(host->mmc);
+
+ host->dma_tx = dma_request_chan(dev, "tx-rx");
+ if (!IS_ERR(host->dma_tx))
+ return 0;
+
+ if (PTR_ERR(host->dma_tx) != -ENODEV) {
+ dev_err(dev, "Failed to get dma tx-rx channel\n");
+ return PTR_ERR(host->dma_tx);
+ }
+
host->dma_tx = dma_request_chan(mmc_dev(host->mmc), "tx");
if (IS_ERR(host->dma_tx)) {
dev_err(mmc_dev(host->mmc), "Failed to get dma_tx channel\n");
@@ -241,7 +253,10 @@ static int jz4740_mmc_acquire_dma_channels(struct jz4740_mmc_host *host)
static inline struct dma_chan *jz4740_mmc_get_dma_chan(struct jz4740_mmc_host *host,
struct mmc_data *data)
{
- return (data->flags & MMC_DATA_READ) ? host->dma_rx : host->dma_tx;
+ if ((data->flags & MMC_DATA_READ) && host->dma_rx)
+ return host->dma_rx;
+ else
+ return host->dma_tx;
}
static void jz4740_mmc_dma_unmap(struct jz4740_mmc_host *host,
--
2.34.1
next prev parent reply other threads:[~2021-12-20 19:09 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-20 19:08 [PATCH 0/2] mmc: ingenic: Support bi-directional DMA channel Paul Cercueil
2021-12-20 19:08 ` [PATCH 1/2] dt-bindings: mmc: ingenic: Support using " Paul Cercueil
2021-12-20 19:08 ` Paul Cercueil [this message]
2021-12-21 13:03 ` [PATCH 0/2] mmc: ingenic: Support " Ulf Hansson
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=20211220190840.108061-3-paul@crapouillou.net \
--to=paul@crapouillou.net \
--cc=devicetree@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mips@vger.kernel.org \
--cc=linux-mmc@vger.kernel.org \
--cc=list@opendingux.net \
--cc=robh+dt@kernel.org \
--cc=ulf.hansson@linaro.org \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
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).