lkml.org 
[lkml]   [2013]   [Jul]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v2] ARM: EDMA: Fix clearing of unused list for DT DMA resources
On Monday 22 July 2013 11:29 PM, Joel Fernandes wrote:
> HWMOD removal for MMC is breaking edma_start as the events are being manually
> triggered due to unused channel list not being clear, Thanks to Balaji TK for
> finding this issue.

So, Reported-by: Balaji T K <balajitk@ti.com>

?

>
> This patch fixes the issue, by reading the "dmas" property from the DT node if
> it exists and clearing the bits in the unused channel list.
>
> Cc: Balaji T K <balajitk@ti.com>
> Cc: Pantel Antoniou <panto@antoniou-consulting.com>
> Signed-off-by: Joel Fernandes <joelf@ti.com>
> ---
> v2 changes: Fixed compiler warning
>
> arch/arm/common/edma.c | 31 +++++++++++++++++++++++--------
> 1 file changed, 23 insertions(+), 8 deletions(-)
>
> diff --git a/arch/arm/common/edma.c b/arch/arm/common/edma.c
> index a432e6c..765d578 100644
> --- a/arch/arm/common/edma.c
> +++ b/arch/arm/common/edma.c
> @@ -561,14 +561,29 @@ static int reserve_contiguous_slots(int ctlr, unsigned int id,
> static int prepare_unused_channel_list(struct device *dev, void *data)
> {
> struct platform_device *pdev = to_platform_device(dev);
> - int i, ctlr;
> -
> - for (i = 0; i < pdev->num_resources; i++) {
> - if ((pdev->resource[i].flags & IORESOURCE_DMA) &&
> - (int)pdev->resource[i].start >= 0) {
> - ctlr = EDMA_CTLR(pdev->resource[i].start);
> - clear_bit(EDMA_CHAN_SLOT(pdev->resource[i].start),
> - edma_cc[ctlr]->edma_unused);
> + int i = 0, ctlr;
> + u32 dma_chan;
> + const __be32 *dma_chan_p;
> + struct property *prop;
> +
> + if (dev->of_node) {
> + of_property_for_each_u32(dev->of_node, "dmas", prop, \
> + dma_chan_p, dma_chan) {
> + if (i++ & 1) {
> + ctlr = EDMA_CTLR(dma_chan);
> + clear_bit(EDMA_CHAN_SLOT(dma_chan),
> + edma_cc[ctlr]->edma_unused);
> + }

I think it will be cleaner if you use of_property_count_strings() on
dma-names to get the count of DMA channels for this device and then use
of_parse_phandle_with_args() to get access to the args. Honestly, I have
not used these APIs myself, so if this doesn’t work the way I think it
should then let me know and I will try to do some experiments myself.

The current way of skipping over even fields really depends on
#dma-cells for EDMA to be 1. That in itself is not such a bad
assumption, but if you have APIs which already take care of this for
you, why not use them?

> + }
> + } else {
> + for (; i < pdev->num_resources; i++) {
> + if ((pdev->resource[i].flags & IORESOURCE_DMA) &&
> + (int)pdev->resource[i].start >= 0) {
> + ctlr = EDMA_CTLR(pdev->resource[i].start);
> + clear_bit(EDMA_CHAN_SLOT(
> + pdev->resource[i].start),
> + edma_cc[ctlr]->edma_unused);
> + }

So there is very little in common between OF and non-OF versions of this
function. Why not have two different versions of this function for the
two cases? The OF version can reside under the CONFIG_OF conditional
already in use in the file. This will also save you the ugly line breaks
you had to resort to due to too deep indentation.

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

\
 
 \ /
  Last update: 2013-07-29 09:21    [W:0.116 / U:1.628 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site