On Fri, Jun 29, 2018 at 9:37 AM, Vinod <vk...@kernel.org> wrote:
> On 25-06-18, 11:27, Andrea Merello wrote:
>> The AXIDMA and CDMA HW can be either direct-access or scatter-gather
>> version. These are SW incompatible.
>>
>> The driver can handle both version: a DT property was used to
> ^^^^
> versions
>
OK
>> tell the driver whether to assume the HW is is scatter-gather mode.
> ^^^^^
> is in?
Yes, it is. Thanks
>>
>> This patch makes the driver to autodetect this information. The DT
>> property is not required anymore.
>>
>> No changes for VDMA.
>>
>> Cc: Rob Herring <robh...@kernel.org>
>> Cc: Mark Rutland <mark.rutl...@arm.com>
>> Cc: devicet...@vger.kernel.org
>> Cc: Radhey Shyam Pandey <radhey.shyam.pan...@xilinx.com>
>> Signed-off-by: Andrea Merello <andrea.mere...@gmail.com>
>> Reviewed-by: Radhey Shyam Pandey <radhey.shyam.pan...@xilinx.com>
>> ---
>> Changes in v2:
>> - autodetect only in !VDMA case
>> Changes in v3:
>> - cc DT maintainers/ML
>> ---
>> drivers/dma/xilinx/xilinx_dma.c | 14 ++++++++++----
>> 1 file changed, 10 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/dma/xilinx/xilinx_dma.c
>> b/drivers/dma/xilinx/xilinx_dma.c
>> index 7f0ab904b749..43fcc71ff287 100644
>> --- a/drivers/dma/xilinx/xilinx_dma.c
>> +++ b/drivers/dma/xilinx/xilinx_dma.c
>> @@ -86,6 +86,7 @@
>> #define XILINX_DMA_DMASR_DMA_DEC_ERR BIT(6)
>> #define XILINX_DMA_DMASR_DMA_SLAVE_ERR BIT(5)
>> #define XILINX_DMA_DMASR_DMA_INT_ERR BIT(4)
>> +#define XILINX_DMA_DMASR_SG_MASK BIT(3)
>> #define XILINX_DMA_DMASR_IDLE BIT(1)
>> #define XILINX_DMA_DMASR_HALTED BIT(0)
>> #define XILINX_DMA_DMASR_DELAY_MASK GENMASK(31, 24)
>> @@ -406,7 +407,6 @@ struct xilinx_dma_config {
>> * @dev: Device Structure
>> * @common: DMA device structure
>> * @chan: Driver specific DMA channel
>> - * @has_sg: Specifies whether Scatter-Gather is present or not
>> * @mcdma: Specifies whether Multi-Channel is present or not
>> * @flush_on_fsync: Flush on frame sync
>> * @ext_addr: Indicates 64 bit addressing is supported by dma device
>> @@ -426,7 +426,6 @@ struct xilinx_dma_device {
>> struct device *dev;
>> struct dma_device common;
>> struct xilinx_dma_chan *chan[XILINX_DMA_MAX_CHANS_PER_DEVICE];
>> - bool has_sg;
>> bool mcdma;
>> u32 flush_on_fsync;
>> bool ext_addr;
>> @@ -2393,7 +2392,6 @@ static int xilinx_dma_chan_probe(struct
>> xilinx_dma_device *xdev,
>>
>> chan->dev = xdev->dev;
>> chan->xdev = xdev;
>> - chan->has_sg = xdev->has_sg;
>> chan->desc_pendingcount = 0x0;
>> chan->ext_addr = xdev->ext_addr;
>> /* This variable ensures that descriptors are not
>> @@ -2486,6 +2484,15 @@ static int xilinx_dma_chan_probe(struct
>> xilinx_dma_device *xdev,
>> chan->stop_transfer = xilinx_dma_stop_transfer;
>> }
>>
>> + /* check if SG is enabled (only for AXIDMA and CDMA) */
>> + if (xdev->dma_config->dmatype != XDMA_TYPE_VDMA) {
>> + if (dma_ctrl_read(chan, XILINX_DMA_REG_DMASR) &
>> + XILINX_DMA_DMASR_SG_MASK)
>
> why not read this for VDMA too, will it return false?
AFAIK this bit is reserved in VDMA, so reading it can lead to any
random thing.. I would say that potentially it could even be used for
other purposes in future IP releases..
>> + chan->has_sg = true;
>> + dev_dbg(chan->dev, "ch %d: SG %s\n", chan->id,
>> + chan->has_sg ? "enabled" : "disabled");
>
> this debug print can be removed
IMHO if someone will ever enable debug prints for debugging something
and then he/she reports us a log, then it would be useful to see in
the log if the IP was SG or not..
> --
> ~Vinod
