[PATCH v6 2/2] dma: Add Xilinx AXI Video Direct Memory Access Engine driver support

On Mon, Mar 24, 2014 at 8:53 PM, Jassi Brar [off-list ref] wrote:

On Mon, Mar 24, 2014 at 8:44 PM, Srikanth Thokala [off-list ref] wrote:

quoted

On Mon, Mar 24, 2014 at 4:21 PM, Jassi Brar [off-list ref] wrote:

quoted

On 24 March 2014 14:30, Srikanth Thokala [off-list ref] wrote:

quoted

Hi Jassi,

Thanks for the Acked-by.

On Mon, Mar 24, 2014 at 11:50 AM, Jassi Brar [off-list ref] wrote:

quoted

On Tue, Mar 18, 2014 at 12:36 AM, Srikanth Thokala [off-list ref] wrote:

quoted

+
+/**
+ * xilinx_vdma_prep_slave_sg - prepare a descriptor for a DMA_SLAVE transaction

Should be xilinx_vdma_dma_prep_interleaved here.

Ok, I will correct it.  Thanks.

quoted

quoted

+/**
+ * xilinx_vdma_channel_set_config - Configure VDMA channel
+ * Run-time configuration for Axi VDMA, supports:
+ * . halt the channel
+ * . configure interrupt coalescing and inter-packet delay threshold
+ * . start/stop parking
+ * . enable genlock
+ *
+ * @dchan: DMA channel
+ * @cfg: VDMA device configuration pointer
+ *
+ * Return: '0' on success and failure value on error
+ */
+int xilinx_vdma_channel_set_config(struct dma_chan *dchan,
+                                       struct xilinx_vdma_config *cfg)
+{
+       struct xilinx_vdma_chan *chan = to_xilinx_chan(dchan);
+       u32 dmacr;
+
+       if (cfg->reset)
+               return xilinx_vdma_chan_reset(chan);
+
+       dmacr = vdma_ctrl_read(chan, XILINX_VDMA_REG_DMACR);
+
+       chan->config.frm_dly = cfg->frm_dly;
+       chan->config.park = cfg->park;
+
+       /* genlock settings */
+       chan->config.gen_lock = cfg->gen_lock;
+       chan->config.master = cfg->master;
+
+       if (cfg->gen_lock && chan->genlock) {
+               dmacr |= XILINX_VDMA_DMACR_GENLOCK_EN;
+               dmacr |= cfg->master << XILINX_VDMA_DMACR_MASTER_SHIFT;
+       }
+
+       chan->config.frm_cnt_en = cfg->frm_cnt_en;
+       if (cfg->park)
+               chan->config.park_frm = cfg->park_frm;
+       else
+               chan->config.park_frm = -1;
+
+       chan->config.coalesc = cfg->coalesc;
+       chan->config.delay = cfg->delay;
+
+       if (cfg->coalesc <= XILINX_VDMA_DMACR_FRAME_COUNT_MAX) {
+               dmacr |= cfg->coalesc << XILINX_VDMA_DMACR_FRAME_COUNT_SHIFT;
+               chan->config.coalesc = cfg->coalesc;
+       }
+
+       if (cfg->delay <= XILINX_VDMA_DMACR_DELAY_MAX) {
+               dmacr |= cfg->delay << XILINX_VDMA_DMACR_DELAY_SHIFT;
+               chan->config.delay = cfg->delay;
+       }
+
+       /* FSync Source selection */
+       dmacr &= ~XILINX_VDMA_DMACR_FSYNCSRC_MASK;
+       dmacr |= cfg->ext_fsync << XILINX_VDMA_DMACR_FSYNCSRC_SHIFT;
+
+       vdma_ctrl_write(chan, XILINX_VDMA_REG_DMACR, dmacr);
+
+       return 0;
+}
+EXPORT_SYMBOL(xilinx_vdma_channel_set_config);
+

Bypassing the DMAEngine api doesn't seem very neat.
Is there currently any client driver that /changes/ this configuration
between channel requests? If no, then simply get the configuration
from DT node and avoid this api.

This change is recently suggested by Lars in the following patch series,
"dma: Remove comment about embedding dma_slave_config into custom structs"

If some user does indeed need to /change/ the configuration across
channel requests, we can keep function. Is there currently any such
user?

Yes, we are planning to push these changes soon to drivers/media/.

This is not what I asked though. I asked if some client driver changes
the configuration options based on some runtime decision? If yes, then
the api is warranted. Otherwise, you might consider getting the static
configuration from DT. That's all I suggest.

Yes, the client driver can change the configuration in the runtime
like the park_frm
option, for example, decides on which frame to park on.

Srikanth

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo at vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/