Re: [PATCH v2] dmaengine: tegra210-adma: fix transfer failure

[Sameer Pujar <spujar@nvidia.com>]

Sorry for delayed reply, I was consumed in some other work.

On 8/19/2019 11:10 PM, Jon Hunter wrote:
> On 12/07/2019 12:10, Sameer Pujar wrote:
>>  From Tegra186 onwards OUTSTANDING_REQUESTS field is added in channel
>> configuration register(bits 7:4) which defines the maximum number of reads
>> from the source and writes to the destination that may be outstanding at
>> any given point of time. This field must be programmed with a value
>> between 1 and 8. A value of 0 will prevent any transfers from happening.
>>
>> Thus added 'ch_pending_req' member in chip data structure and the same is
>> populated with maximum allowed pending requests. Since the field is not
>> applicable to Tegra210, mentioned bit fields are unused and hence the
>> member is initialized with 0. For Tegra186, by default program this field
>> with the maximum permitted value of 8.
>>
>> Fixes: 433de642a76c ("dmaengine: tegra210-adma: add support for Tegra186/Tegra194")
>>
>> Signed-off-by: Sameer Pujar <spujar@nvidia.com>
>> ---
>>   drivers/dma/tegra210-adma.c | 7 +++++++
>>   1 file changed, 7 insertions(+)
>>
>> diff --git a/drivers/dma/tegra210-adma.c b/drivers/dma/tegra210-adma.c
>> index 2805853..5ab4e3a9 100644
>> --- a/drivers/dma/tegra210-adma.c
>> +++ b/drivers/dma/tegra210-adma.c
>> @@ -74,6 +74,8 @@
>>   				    TEGRA186_ADMA_CH_FIFO_CTRL_TXSIZE(3)    | \
>>   				    TEGRA186_ADMA_CH_FIFO_CTRL_RXSIZE(3))
>>   
>> +#define TEGRA186_DMA_MAX_PENDING_REQS			8
>> +
>>   #define ADMA_CH_REG_FIELD_VAL(val, mask, shift)	(((val) & mask) << shift)
>>   
>>   struct tegra_adma;
>> @@ -85,6 +87,7 @@ struct tegra_adma;
>>    * @ch_req_tx_shift: Register offset for AHUB transmit channel select.
>>    * @ch_req_rx_shift: Register offset for AHUB receive channel select.
>>    * @ch_base_offset: Register offset of DMA channel registers.
>> + * @ch_pending_req: Outstaning DMA requests for a channel.
> s/Outstaning/Outstanding
will fix.
> I do wonder if this variable should be a boolean variable
> 'has_oustanding_reqs' because this is not applicable to Tegra210. I
> think this will be clearer that this is a difference between SoC
> versions and that it should not be configured for Tegra210. And then ...
>
>>    * @ch_fifo_ctrl: Default value for channel FIFO CTRL register.
>>    * @ch_req_mask: Mask for Tx or Rx channel select.
>>    * @ch_req_max: Maximum number of Tx or Rx channels available.
>> @@ -98,6 +101,7 @@ struct tegra_adma_chip_data {
>>   	unsigned int ch_req_tx_shift;
>>   	unsigned int ch_req_rx_shift;
>>   	unsigned int ch_base_offset;
>> +	unsigned int ch_pending_req;
>>   	unsigned int ch_fifo_ctrl;
>>   	unsigned int ch_req_mask;
>>   	unsigned int ch_req_max;
>> @@ -602,6 +606,7 @@ static int tegra_adma_set_xfer_params(struct tegra_adma_chan *tdc,
>>   			 ADMA_CH_CTRL_FLOWCTRL_EN;
>>   	ch_regs->config |= cdata->adma_get_burst_config(burst_size);
>>   	ch_regs->config |= ADMA_CH_CONFIG_WEIGHT_FOR_WRR(1);
>> +	ch_regs->config |= cdata->ch_pending_req;
> ... you can ...
>
>          if (cdata->has_outstanding_reqs)
>              ch_regs->config |= TEGRA186_ADMA_CH_CONFIG_OUTSTNDREQS(8)
yes, this can be done. Will update in next revision.
>
>>   	ch_regs->fifo_ctrl = cdata->ch_fifo_ctrl;
>>   	ch_regs->tc = desc->period_len & ADMA_CH_TC_COUNT_MASK;
>>   
>> @@ -786,6 +791,7 @@ static const struct tegra_adma_chip_data tegra210_chip_data = {
>>   	.ch_req_tx_shift	= 28,
>>   	.ch_req_rx_shift	= 24,
>>   	.ch_base_offset		= 0,
>> +	.ch_pending_req		= 0,
>>   	.ch_fifo_ctrl		= TEGRA210_FIFO_CTRL_DEFAULT,
>>   	.ch_req_mask		= 0xf,
>>   	.ch_req_max		= 10,
>> @@ -800,6 +806,7 @@ static const struct tegra_adma_chip_data tegra186_chip_data = {
>>   	.ch_req_tx_shift	= 27,
>>   	.ch_req_rx_shift	= 22,
>>   	.ch_base_offset		= 0x10000,
>> +	.ch_pending_req		= (TEGRA186_DMA_MAX_PENDING_REQS << 4),
>>   	.ch_fifo_ctrl		= TEGRA186_FIFO_CTRL_DEFAULT,
>>   	.ch_req_mask		= 0x1f,
>>   	.ch_req_max		= 20,
>>