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Date:   Tue, 4 Apr 2023 23:23:52 +0300
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To:     Siddharth Vadapalli <s-vadapalli@ti.com>, vkoul@kernel.org
Cc:     dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, srk@ti.com, vigneshr@ti.com
References: <20230404081158.1266530-1-s-vadapalli@ti.com>
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From:   =?UTF-8?Q?P=c3=a9ter_Ujfalusi?= <peter.ujfalusi@gmail.com>
Subject: Re: [PATCH] dmaengine: ti: k3-udma-glue: do not create glue dma
 devices for udma channels
In-Reply-To: <20230404081158.1266530-1-s-vadapalli@ti.com>
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On 04/04/2023 11:11, Siddharth Vadapalli wrote:
> From: Grygorii Strashko <grygorii.strashko@ti.com>
> 
> In case K3 DMA glue layer is using UDMA channels (AM65/J721E/J7200) it
> doesn't need to create own DMA devices per RX/TX channels as they are never
> used and just waste resources. The UDMA based platforms are coherent and
> UDMA device iteslf is used for DMA memory management.
> 
> Hence, update K3 DMA glue layer to create K3 DMA glue DMA devices per RX/TX
> channels only in case of PKTDMA (AM64) where coherency configurable per DMA
> channel.
> 
> Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
> Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>
> ---
>   drivers/dma/ti/k3-udma-glue.c | 70 +++++++++++++++++------------------
>   1 file changed, 34 insertions(+), 36 deletions(-)
> 
> diff --git a/drivers/dma/ti/k3-udma-glue.c b/drivers/dma/ti/k3-udma-glue.c
> index 789193ed0386..b0c9572b0d02 100644
> --- a/drivers/dma/ti/k3-udma-glue.c
> +++ b/drivers/dma/ti/k3-udma-glue.c
> @@ -293,19 +293,18 @@ struct k3_udma_glue_tx_channel *k3_udma_glue_request_tx_chn(struct device *dev,
>   	}
>   	tx_chn->udma_tchan_id = xudma_tchan_get_id(tx_chn->udma_tchanx);
>   
> -	tx_chn->common.chan_dev.class = &k3_udma_glue_devclass;
> -	tx_chn->common.chan_dev.parent = xudma_get_device(tx_chn->common.udmax);
> -	dev_set_name(&tx_chn->common.chan_dev, "tchan%d-0x%04x",
> -		     tx_chn->udma_tchan_id, tx_chn->common.dst_thread);
> -	ret = device_register(&tx_chn->common.chan_dev);
> -	if (ret) {
> -		dev_err(dev, "Channel Device registration failed %d\n", ret);
> -		put_device(&tx_chn->common.chan_dev);
> -		tx_chn->common.chan_dev.parent = NULL;
> -		goto err;
> -	}
> -
>   	if (xudma_is_pktdma(tx_chn->common.udmax)) {

it might be possible to narrow it down to include a test for atype_asel 
14 or 15, but then I would move that test to a helper (passing common as 
parameter) and re-use it in other places to avoid getting out o sync 
overtime.
Might not worth the effort, just an observation.

> +		tx_chn->common.chan_dev.class = &k3_udma_glue_devclass;
> +		tx_chn->common.chan_dev.parent = xudma_get_device(tx_chn->common.udmax);
> +		dev_set_name(&tx_chn->common.chan_dev, "tchan%d-0x%04x",
> +			     tx_chn->udma_tchan_id, tx_chn->common.dst_thread);
> +		ret = device_register(&tx_chn->common.chan_dev);
> +		if (ret) {
> +			dev_err(dev, "Channel Device registration failed %d\n", ret);

my guess is that the put_device() is still needed, no?

> +			tx_chn->common.chan_dev.parent = NULL;
> +			goto err;
> +		}
> +
>   		/* prepare the channel device as coherent */
>   		tx_chn->common.chan_dev.dma_coherent = true;
>   		dma_coerce_mask_and_coherent(&tx_chn->common.chan_dev,
> @@ -912,19 +911,18 @@ k3_udma_glue_request_rx_chn_priv(struct device *dev, const char *name,
>   	}
>   	rx_chn->udma_rchan_id = xudma_rchan_get_id(rx_chn->udma_rchanx);
>   
> -	rx_chn->common.chan_dev.class = &k3_udma_glue_devclass;
> -	rx_chn->common.chan_dev.parent = xudma_get_device(rx_chn->common.udmax);
> -	dev_set_name(&rx_chn->common.chan_dev, "rchan%d-0x%04x",
> -		     rx_chn->udma_rchan_id, rx_chn->common.src_thread);
> -	ret = device_register(&rx_chn->common.chan_dev);
> -	if (ret) {
> -		dev_err(dev, "Channel Device registration failed %d\n", ret);
> -		put_device(&rx_chn->common.chan_dev);
> -		rx_chn->common.chan_dev.parent = NULL;
> -		goto err;
> -	}
> -
>   	if (xudma_is_pktdma(rx_chn->common.udmax)) {
> +		rx_chn->common.chan_dev.class = &k3_udma_glue_devclass;
> +		rx_chn->common.chan_dev.parent = xudma_get_device(rx_chn->common.udmax);
> +		dev_set_name(&rx_chn->common.chan_dev, "rchan%d-0x%04x",
> +			     rx_chn->udma_rchan_id, rx_chn->common.src_thread);
> +		ret = device_register(&rx_chn->common.chan_dev);
> +		if (ret) {
> +			dev_err(dev, "Channel Device registration failed %d\n", ret);
> +			rx_chn->common.chan_dev.parent = NULL;
> +			goto err;
> +		}
> +
>   		/* prepare the channel device as coherent */
>   		rx_chn->common.chan_dev.dma_coherent = true;
>   		dma_coerce_mask_and_coherent(&rx_chn->common.chan_dev,
> @@ -1044,19 +1042,19 @@ k3_udma_glue_request_remote_rx_chn(struct device *dev, const char *name,
>   		goto err;
>   	}
>   
> -	rx_chn->common.chan_dev.class = &k3_udma_glue_devclass;
> -	rx_chn->common.chan_dev.parent = xudma_get_device(rx_chn->common.udmax);
> -	dev_set_name(&rx_chn->common.chan_dev, "rchan_remote-0x%04x",
> -		     rx_chn->common.src_thread);
> -	ret = device_register(&rx_chn->common.chan_dev);
> -	if (ret) {
> -		dev_err(dev, "Channel Device registration failed %d\n", ret);
> -		put_device(&rx_chn->common.chan_dev);
> -		rx_chn->common.chan_dev.parent = NULL;
> -		goto err;
> -	}
> -
>   	if (xudma_is_pktdma(rx_chn->common.udmax)) {
> +		rx_chn->common.chan_dev.class = &k3_udma_glue_devclass;
> +		rx_chn->common.chan_dev.parent = xudma_get_device(rx_chn->common.udmax);
> +		dev_set_name(&rx_chn->common.chan_dev, "rchan_remote-0x%04x",
> +			     rx_chn->common.src_thread);
> +
> +		ret = device_register(&rx_chn->common.chan_dev);
> +		if (ret) {
> +			dev_err(dev, "Channel Device registration failed %d\n", ret);
> +			rx_chn->common.chan_dev.parent = NULL;
> +			goto err;
> +		}
> +
>   		/* prepare the channel device as coherent */
>   		rx_chn->common.chan_dev.dma_coherent = true;
>   		dma_coerce_mask_and_coherent(&rx_chn->common.chan_dev,

-- 
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