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Subject: Re: [PATCH v2] dmaengine: tegra210-adma: fix transfer failure
To:     Sameer Pujar <spujar@nvidia.com>, <vkoul@kernel.org>,
        <ldewangan@nvidia.com>
CC:     <thierry.reding@gmail.com>, <dmaengine@vger.kernel.org>,
        <linux-tegra@vger.kernel.org>
References: <1562929830-29344-1-git-send-email-spujar@nvidia.com>
From:   Jon Hunter <jonathanh@nvidia.com>
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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

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)

>  	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,
> 

-- 
nvpublic