[BONUS PATCH] dmaengine: dw_dmac: simplify master selection

From: Arnd Bergmann
Date: Sat Feb 16 2013 - 17:23:29 EST

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The patch to add the common DMA binding added a dummy dw_dma_slave
structure into the dw_dma_chan structure in order to configure the
masters correctly. It turns out that this can be simplified if we
pick the DMA masters in the dwc_alloc_chan_resources function instead
and save them in the dw_dma_chan structure directly.

This could be simplified further once all users that today use
dw_dma_slave for configuration get converted to device tree based
setup instead.

This is just a proof of concept patch and should not get merged in
3.9, but I hope that Andy and Viresh find it useful and submit it
for 3.10 after testing and refining it.

Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Cc: Vinod Koul <vinod.koul@xxxxxxxxxxxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
---
drivers/dma/dw_dmac.c | 96 ++++++++++++++++------------------------------
drivers/dma/dw_dmac_regs.h | 4 +-
2 files changed, 36 insertions(+), 64 deletions(-)

diff --git a/drivers/dma/dw_dmac.c b/drivers/dma/dw_dmac.c
index 72d6abf..72c6f6d 100644
--- a/drivers/dma/dw_dmac.c
+++ b/drivers/dma/dw_dmac.c
@@ -37,40 +37,10 @@
* The driver has currently been tested only with the Atmel AT32AP7000,
* which does not support descriptor writeback.
*/
-
-static inline unsigned int dwc_get_dms(struct dw_dma_slave *slave)
-{
- return slave ? slave->dst_master : 0;
-}
-
-static inline unsigned int dwc_get_sms(struct dw_dma_slave *slave)
-{
- return slave ? slave->src_master : 1;
-}
-
-#define SRC_MASTER 0
-#define DST_MASTER 1
-
-static inline unsigned int dwc_get_master(struct dma_chan *chan, int master)
-{
- struct dw_dma *dw = to_dw_dma(chan->device);
- struct dw_dma_slave *dws = chan->private;
- unsigned int m;
-
- if (master == SRC_MASTER)
- m = dwc_get_sms(dws);
- else
- m = dwc_get_dms(dws);
-
- return min_t(unsigned int, dw->nr_masters - 1, m);
-}
-
#define DWC_DEFAULT_CTLLO(_chan) ({ \
struct dw_dma_chan *_dwc = to_dw_dma_chan(_chan); \
struct dma_slave_config *_sconfig = &_dwc->dma_sconfig; \
bool _is_slave = is_slave_direction(_dwc->direction); \
- int _dms = dwc_get_master(_chan, DST_MASTER); \
- int _sms = dwc_get_master(_chan, SRC_MASTER); \
u8 _smsize = _is_slave ? _sconfig->src_maxburst : \
DW_DMA_MSIZE_16; \
u8 _dmsize = _is_slave ? _sconfig->dst_maxburst : \
@@ -80,8 +50,8 @@ static inline unsigned int dwc_get_master(struct dma_chan *chan, int master)
| DWC_CTLL_SRC_MSIZE(_smsize) \
| DWC_CTLL_LLP_D_EN \
| DWC_CTLL_LLP_S_EN \
- | DWC_CTLL_DMS(_dms) \
- | DWC_CTLL_SMS(_sms)); \
+ | DWC_CTLL_DMS(_dwc->dst_master) \
+ | DWC_CTLL_SMS(_dwc->src_master)); \
})

/*
@@ -91,13 +61,6 @@ static inline unsigned int dwc_get_master(struct dma_chan *chan, int master)
*/
#define NR_DESCS_PER_CHANNEL 64

-static inline unsigned int dwc_get_data_width(struct dma_chan *chan, int master)
-{
- struct dw_dma *dw = to_dw_dma(chan->device);
-
- return dw->data_width[dwc_get_master(chan, master)];
-}
-
/*----------------------------------------------------------------------*/

static struct device *chan2dev(struct dma_chan *chan)
@@ -171,13 +134,7 @@ static void dwc_initialize(struct dw_dma_chan *dwc)
if (dwc->initialized == true)
return;

- if (dws && dws->cfg_hi == ~0 && dws->cfg_lo == ~0) {
- /* autoconfigure based on request line from DT */
- if (dwc->direction == DMA_MEM_TO_DEV)
- cfghi = DWC_CFGH_DST_PER(dwc->request_line);
- else if (dwc->direction == DMA_DEV_TO_MEM)
- cfghi = DWC_CFGH_SRC_PER(dwc->request_line);
- } else if (dws) {
+ if (dws) {
/*
* We need controller-specific data to set up slave
* transfers.
@@ -187,10 +144,12 @@ static void dwc_initialize(struct dw_dma_chan *dwc)
cfghi = dws->cfg_hi;
cfglo |= dws->cfg_lo & ~DWC_CFGL_CH_PRIOR_MASK;
} else {
+ unsigned int request_line = (dwc->request_line != ~0) ?
+ dwc->request_line : dwc->dma_sconfig.slave_id;
if (dwc->direction == DMA_MEM_TO_DEV)
- cfghi = DWC_CFGH_DST_PER(dwc->dma_sconfig.slave_id);
+ cfghi = DWC_CFGH_DST_PER(request_line);
else if (dwc->direction == DMA_DEV_TO_MEM)
- cfghi = DWC_CFGH_SRC_PER(dwc->dma_sconfig.slave_id);
+ cfghi = DWC_CFGH_SRC_PER(request_line);
}

channel_writel(dwc, CFG_LO, cfglo);
@@ -743,6 +702,7 @@ static struct dma_async_tx_descriptor *
dwc_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
size_t len, unsigned long flags)
{
+ struct dw_dma *dw = to_dw_dma(chan->device);
struct dw_dma_chan *dwc = to_dw_dma_chan(chan);
struct dw_desc *desc;
struct dw_desc *first;
@@ -766,8 +726,7 @@ dwc_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,

dwc->direction = DMA_MEM_TO_MEM;

- data_width = min_t(unsigned int, dwc_get_data_width(chan, SRC_MASTER),
- dwc_get_data_width(chan, DST_MASTER));
+ data_width = min(dw->data_width[dwc->src_master], dw->data_width[dwc->dst_master]);

src_width = dst_width = min_t(unsigned int, data_width,
dwc_fast_fls(src | dest | len));
@@ -824,6 +783,7 @@ dwc_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
unsigned int sg_len, enum dma_transfer_direction direction,
unsigned long flags, void *context)
{
+ struct dw_dma *dw = to_dw_dma(chan->device);
struct dw_dma_chan *dwc = to_dw_dma_chan(chan);
struct dma_slave_config *sconfig = &dwc->dma_sconfig;
struct dw_desc *prev;
@@ -858,7 +818,7 @@ dwc_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
ctllo |= sconfig->device_fc ? DWC_CTLL_FC(DW_DMA_FC_P_M2P) :
DWC_CTLL_FC(DW_DMA_FC_D_M2P);

- data_width = dwc_get_data_width(chan, SRC_MASTER);
+ data_width = dw->data_width[dwc->src_master];

for_each_sg(sgl, sg, sg_len, i) {
struct dw_desc *desc;
@@ -918,7 +878,7 @@ slave_sg_todev_fill_desc:
ctllo |= sconfig->device_fc ? DWC_CTLL_FC(DW_DMA_FC_P_P2M) :
DWC_CTLL_FC(DW_DMA_FC_D_P2M);

- data_width = dwc_get_data_width(chan, DST_MASTER);
+ data_width = dw->data_width[dwc->dst_master];

for_each_sg(sgl, sg, sg_len, i) {
struct dw_desc *desc;
@@ -1139,6 +1099,7 @@ static void dwc_issue_pending(struct dma_chan *chan)
static int dwc_alloc_chan_resources(struct dma_chan *chan)
{
struct dw_dma_chan *dwc = to_dw_dma_chan(chan);
+ struct dw_dma_slave *dws = chan->private;
struct dw_dma *dw = to_dw_dma(chan->device);
struct dw_desc *desc;
int i;
@@ -1153,6 +1114,17 @@ static int dwc_alloc_chan_resources(struct dma_chan *chan)
}

dma_cookie_init(chan);
+ /* masters may be set up from dws, from DT or autoconfigured here */
+ if (dws) {
+ dwc->src_master = dws->src_master;
+ dwc->dst_master = dws->dst_master;
+ }
+ /* if unconfigured, default to source 1 dest 0 */
+ if (dwc->src_master == ~0)
+ dwc->src_master = 1;
+ if (dwc->dst_master == ~0)
+ dwc->dst_master = 0;
+

/*
* NOTE: some controllers may have additional features that we
@@ -1218,6 +1190,10 @@ static void dwc_free_chan_resources(struct dma_chan *chan)
dwc->descs_allocated = 0;
dwc->initialized = false;

+ /* invalidate slave configuration */
+ dwc->request_line = ~0;
+ dwc->src_master = dwc->dst_master = ~0;
+
/* Disable interrupts */
channel_clear_bit(dw, MASK.XFER, dwc->mask);
channel_clear_bit(dw, MASK.ERROR, dwc->mask);
@@ -1242,23 +1218,15 @@ struct dw_dma_filter_args {
static bool dw_dma_generic_filter(struct dma_chan *chan, void *param)
{
struct dw_dma_chan *dwc = to_dw_dma_chan(chan);
- struct dw_dma *dw = to_dw_dma(chan->device);
struct dw_dma_filter_args *fargs = param;
- struct dw_dma_slave *dws = &dwc->slave;

/* ensure the device matches our channel */
if (chan->device != &fargs->dw->dma)
return false;

- dws->dma_dev = dw->dma.dev;
- dws->cfg_hi = ~0;
- dws->cfg_lo = ~0;
- dws->src_master = fargs->src;
- dws->dst_master = fargs->dst;
-
dwc->request_line = fargs->req;
-
- chan->private = dws;
+ dwc->src_master = fargs->src;
+ dwc->dst_master = fargs->dst;

return true;
}
@@ -1767,6 +1735,10 @@ static int dw_probe(struct platform_device *pdev)

dwc->direction = DMA_TRANS_NONE;

+ /* invalidate slave configuration */
+ dwc->request_line = ~0;
+ dwc->src_master = dwc->dst_master = ~0;
+
/* hardware configuration */
if (autocfg) {
unsigned int dwc_params;
diff --git a/drivers/dma/dw_dmac_regs.h b/drivers/dma/dw_dmac_regs.h
index b632082..fa4e5f7 100644
--- a/drivers/dma/dw_dmac_regs.h
+++ b/drivers/dma/dw_dmac_regs.h
@@ -213,8 +213,8 @@ struct dw_dma_chan {
unsigned int block_size;
bool nollp;
unsigned int request_line;
- struct dw_dma_slave slave;
-
+ unsigned char src_master;
+ unsigned char dst_master;

/* configuration passed via DMA_SLAVE_CONFIG */
struct dma_slave_config dma_sconfig;
--
1.8.1.2

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Next message: Alexey Khoroshilov: "[PATCH] tty: mxser: improve error handling in mxser_probe() and mxser_module_init()"
Previous message: Arnd Bergmann: "[PATCHv3 2/4] dmaengine: dw_dmac: move to generic DMA binding"
In reply to: Arnd Bergmann: "Re: [PATCHv3 2/4] dmaengine: dw_dmac: move to generic DMA binding"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]