From: Andrea Merello <andrea.merello@gmail.com>
To: Vinod <vkoul@kernel.org>
Cc: dan.j.williams@intel.com, michal.simek@xilinx.com,
appana.durga.rao@xilinx.com, dmaengine@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel <linux-kernel@vger.kernel.org>,
Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
devicetree <devicetree@vger.kernel.org>,
Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>
Subject: Re: [PATCH v3 4/5] dmaengine: xilinx_dma: autodetect whether the HW supports scatter-gather
Date: Fri, 29 Jun 2018 09:53:11 +0200 [thread overview]
Message-ID: <CAN8YU5Mmzko0DeoCbCCpS7DyahrUddqWf+PxZNxT3rHanJT-Ag@mail.gmail.com> (raw)
In-Reply-To: <20180629073707.GZ22377@vkoul-mobl>
On Fri, Jun 29, 2018 at 9:37 AM, Vinod <vkoul@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+dt@kernel.org>
>> Cc: Mark Rutland <mark.rutland@arm.com>
>> Cc: devicetree@vger.kernel.org
>> Cc: Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>
>> Signed-off-by: Andrea Merello <andrea.merello@gmail.com>
>> Reviewed-by: Radhey Shyam Pandey <radhey.shyam.pandey@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
next prev parent reply other threads:[~2018-06-29 7:53 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-25 9:27 [PATCH v3 1/5] dmaengine: xilinx_dma: in axidma slave_sg and dma_cylic mode align split descriptors Andrea Merello
2018-06-25 9:27 ` [PATCH v3 2/5] dt-bindings: dmaengine: xilinx_dma: add optional xlnx,sg-length-width property Andrea Merello
2018-06-25 17:29 ` Rob Herring
2018-06-25 9:27 ` [PATCH v3 3/5] dmaengine: xilinx_dma: program hardware supported buffer length Andrea Merello
2018-06-25 9:27 ` [PATCH v3 4/5] dmaengine: xilinx_dma: autodetect whether the HW supports scatter-gather Andrea Merello
2018-06-29 7:37 ` Vinod
2018-06-29 7:53 ` Andrea Merello [this message]
2018-06-25 9:27 ` [PATCH v3 5/5] dt-bindings: dmaengine: xilinx_dma: drop has-sg property Andrea Merello
2018-06-25 17:30 ` Rob Herring
2018-06-29 7:25 ` [PATCH v3 1/5] dmaengine: xilinx_dma: in axidma slave_sg and dma_cylic mode align split descriptors Vinod
2018-06-29 7:46 ` Andrea Merello
2018-06-29 8:19 ` Vinod
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