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authorWolfram Sang <wsa+renesas@sang-engineering.com>2014-12-16 13:31:26 +0100
committerWolfram Sang <wsa@the-dreams.de>2014-12-17 19:26:08 +0100
commit55f5f9862a31e2ac9defea5f30e413d331d1f932 (patch)
treeccefc8ac5c8122a5afd37506d1a9d9817031eb1c /drivers/i2c
parente844a7997dfbce687c7afa9d40f8a3b278e08735 (diff)
downloadlinux-55f5f9862a31e2ac9defea5f30e413d331d1f932.tar.bz2
i2c: sh_mobile: rework deferred probing
DMA is opt-in for this driver. So, we can't use deferred probing for requesting DMA channels in probe, because our driver would get endlessly deferred if DMA support is compiled in AND the DMA driver is missing. Because we can't know when the DMA driver might show up, we always try again when a DMA transfer would be possible. The downside is that there is more overhead for setting up PIO transfers under the above scenario. But well, having DMA enabled and the proper DMA driver missing looks like a broken or test config anyhow. Reported-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'drivers/i2c')
-rw-r--r--drivers/i2c/busses/i2c-sh_mobile.c98
1 files changed, 48 insertions, 50 deletions
diff --git a/drivers/i2c/busses/i2c-sh_mobile.c b/drivers/i2c/busses/i2c-sh_mobile.c
index b49e946b2940..a12297e7680a 100644
--- a/drivers/i2c/busses/i2c-sh_mobile.c
+++ b/drivers/i2c/busses/i2c-sh_mobile.c
@@ -140,6 +140,7 @@ struct sh_mobile_i2c_data {
int sr;
bool send_stop;
+ struct resource *res;
struct dma_chan *dma_tx;
struct dma_chan *dma_rx;
struct scatterlist sg;
@@ -539,6 +540,41 @@ static void sh_mobile_i2c_dma_callback(void *data)
iic_set_clr(pd, ICIC, 0, ICIC_TDMAE | ICIC_RDMAE);
}
+static struct dma_chan *sh_mobile_i2c_request_dma_chan(struct device *dev,
+ enum dma_transfer_direction dir, dma_addr_t port_addr)
+{
+ struct dma_chan *chan;
+ struct dma_slave_config cfg;
+ char *chan_name = dir == DMA_MEM_TO_DEV ? "tx" : "rx";
+ int ret;
+
+ chan = dma_request_slave_channel_reason(dev, chan_name);
+ if (IS_ERR(chan)) {
+ dev_dbg(dev, "request_channel failed for %s (%d)\n", chan_name, ret);
+ return chan;
+ }
+
+ memset(&cfg, 0, sizeof(cfg));
+ cfg.direction = dir;
+ if (dir == DMA_MEM_TO_DEV) {
+ cfg.dst_addr = port_addr;
+ cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+ } else {
+ cfg.src_addr = port_addr;
+ cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+ }
+
+ ret = dmaengine_slave_config(chan, &cfg);
+ if (ret) {
+ dev_dbg(dev, "slave_config failed for %s (%d)\n", chan_name, ret);
+ dma_release_channel(chan);
+ return ERR_PTR(ret);
+ }
+
+ dev_dbg(dev, "got DMA channel for %s\n", chan_name);
+ return chan;
+}
+
static void sh_mobile_i2c_xfer_dma(struct sh_mobile_i2c_data *pd)
{
bool read = pd->msg->flags & I2C_M_RD;
@@ -548,6 +584,15 @@ static void sh_mobile_i2c_xfer_dma(struct sh_mobile_i2c_data *pd)
dma_addr_t dma_addr;
dma_cookie_t cookie;
+ if (PTR_ERR(chan) == -EPROBE_DEFER) {
+ if (read)
+ chan = pd->dma_rx = sh_mobile_i2c_request_dma_chan(pd->dev, DMA_DEV_TO_MEM,
+ pd->res->start + ICDR);
+ else
+ chan = pd->dma_tx = sh_mobile_i2c_request_dma_chan(pd->dev, DMA_MEM_TO_DEV,
+ pd->res->start + ICDR);
+ }
+
if (IS_ERR(chan))
return;
@@ -747,41 +792,6 @@ static const struct of_device_id sh_mobile_i2c_dt_ids[] = {
};
MODULE_DEVICE_TABLE(of, sh_mobile_i2c_dt_ids);
-static struct dma_chan *sh_mobile_i2c_request_dma_chan(struct device *dev,
- enum dma_transfer_direction dir, dma_addr_t port_addr)
-{
- struct dma_chan *chan;
- struct dma_slave_config cfg;
- char *chan_name = dir == DMA_MEM_TO_DEV ? "tx" : "rx";
- int ret;
-
- chan = dma_request_slave_channel_reason(dev, chan_name);
- if (IS_ERR(chan)) {
- dev_dbg(dev, "request_channel failed for %s (%d)\n", chan_name, ret);
- return chan;
- }
-
- memset(&cfg, 0, sizeof(cfg));
- cfg.direction = dir;
- if (dir == DMA_MEM_TO_DEV) {
- cfg.dst_addr = port_addr;
- cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
- } else {
- cfg.src_addr = port_addr;
- cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
- }
-
- ret = dmaengine_slave_config(chan, &cfg);
- if (ret) {
- dev_dbg(dev, "slave_config failed for %s (%d)\n", chan_name, ret);
- dma_release_channel(chan);
- return ERR_PTR(ret);
- }
-
- dev_dbg(dev, "got DMA channel for %s\n", chan_name);
- return chan;
-}
-
static void sh_mobile_i2c_release_dma(struct sh_mobile_i2c_data *pd)
{
if (!IS_ERR(pd->dma_tx)) {
@@ -844,6 +854,7 @@ static int sh_mobile_i2c_probe(struct platform_device *dev)
res = platform_get_resource(dev, IORESOURCE_MEM, 0);
+ pd->res = res;
pd->reg = devm_ioremap_resource(&dev->dev, res);
if (IS_ERR(pd->reg))
return PTR_ERR(pd->reg);
@@ -884,19 +895,7 @@ static int sh_mobile_i2c_probe(struct platform_device *dev)
/* Init DMA */
sg_init_table(&pd->sg, 1);
pd->dma_direction = DMA_NONE;
- pd->dma_rx = sh_mobile_i2c_request_dma_chan(pd->dev, DMA_DEV_TO_MEM,
- res->start + ICDR);
- ret = PTR_ERR(pd->dma_rx);
- if (ret == -EPROBE_DEFER)
- return ret;
-
- pd->dma_tx = sh_mobile_i2c_request_dma_chan(pd->dev, DMA_MEM_TO_DEV,
- res->start + ICDR);
- ret = PTR_ERR(pd->dma_tx);
- if (ret == -EPROBE_DEFER) {
- sh_mobile_i2c_release_dma(pd);
- return ret;
- }
+ pd->dma_rx = pd->dma_tx = ERR_PTR(-EPROBE_DEFER);
/* Enable Runtime PM for this device.
*
@@ -934,8 +933,7 @@ static int sh_mobile_i2c_probe(struct platform_device *dev)
return ret;
}
- dev_info(&dev->dev, "I2C adapter %d, bus speed %lu Hz, DMA=%c\n",
- adap->nr, pd->bus_speed, (pd->dma_rx || pd->dma_tx) ? 'y' : 'n');
+ dev_info(&dev->dev, "I2C adapter %d, bus speed %lu Hz\n", adap->nr, pd->bus_speed);
return 0;
}