On 13.01.2016 14:23, Vinod Koul wrote:
On Thu, Jan 07, 2016 at 05:33:04PM +0000, kernel@xxxxxxxxxxxxxxxx wrote:
+static inline bool bcm2835_dma_is_lite(struct bcm2835_chan *c)
+{
+ /* dma channels >= 7 are LITE channels */
+ return (c->ch >= 7);
Why not DT data here as well
See other email with comments on DT.
+}
+
+static inline size_t bcm2835_dma_max_frame_length(struct bcm2835_chan *c)
+{
+ /* lite and normal channels have different max frame length */
+ return bcm2835_dma_is_lite(c) ? MAX_LITE_DMA_LEN : MAX_DMA_LEN;
Or rather get length from DT..
See other email with comments on DT.
+ /* allocate and setup the descriptor. */
+ d = kzalloc(sizeof(*d) + frames * sizeof(struct bcm2835_cb_entry),
+ gfp);
odd style.. btw should flag be GFP_NOWAIT ..?
gfp was used as a method-argument - see your comment below.
+ /* fill in the control block */
+ control_block = cb_entry->cb;
+ control_block->info = info;
+ control_block->src = src;
+ control_block->dst = dst;
+ if (buf_len) {
+ control_block->length = min(max_len, len);
+ if (period_len &&
+ (total_len + control_block->length >=
+ period_len)) {
+ /* set to end of period_len */
+ control_block->length =
+ period_len - total_len;
+ /* add extrainfo when cyclic */
+ if (cyclic)
+ control_block->info |=
+ finalextrainfo;
+ /* and reset total_len */
+ total_len = 0;
+ }
this looks hard to read, perhpas a helper will make it look better
Perhaps - I can look...
+ /* the last frame requires extra flags */
+ d->cb_list[d->frames - 1].cb->info |= finalextrainfo;
+
+ /* check the size - if there is some missmatch,
+ * then this is detected here
+ */
this is not kernel style for multi-line comments
I know - this came up with a different patch-set
/* Grab configuration */
if (!is_slave_direction(direction)) {
- dev_err(chan->device->dev, "%s: bad direction?\n", __func__);
+ dev_err(chan->device->dev,
+ "%s: bad direction?\n", __func__);
unrelated change
OK
- /* Now allocate and setup the descriptor. */
- d = kzalloc(sizeof(*d), GFP_NOWAIT);
- if (!d)
- return NULL;
+ /* warn if buf_len is not a multiple of period_lenas this may leed
+ * to unexpected latencies for interrupts and thus audiable clicks
+ */
here too
as this code is new and there are a few more issues that have been seen
it was included here...
/*
- * Iterate over all frames, create a control block
- * for each frame and link them together.
+ * allocate the CB chain
+ * note that we need to use GFP_ATOMIC, as the ALSA i2s dmaengine
dmaengine drivers use GFP_NOWAIT in these cases
OK we were not sure if this was "permissible" or would result in rare
issues...
I will wait on the generic DT discussion before sending any updates
incorporating both...
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