linux-kernel - Re: [PATCH v2 3/3] dmaengine: tegra: Add support for dma-channel-mask

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Date:   Fri, 23 Sep 2022 11:08:55 +0100
From:   Jon Hunter <jonathanh@...dia.com>
To:     Akhil R <akhilrajeev@...dia.com>, ldewangan@...dia.com,
        vkoul@...nel.org, thierry.reding@...il.com, p.zabel@...gutronix.de,
        dmaengine@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/3] dmaengine: tegra: Add support for dma-channel-mask



On 19/09/2022 12:25, Akhil R wrote:
> Add support for dma-channel-mask so that only the specified channels
> are used. This helps to reserve some channels for the firmware.
> 
> This was initially achieved by limiting the channel number to 31 in
> the driver and adjusting the register address to skip channel0 which
> was reserved for a firmware. Now, with this change, the driver can
> align more to the actual hardware which has 32 channels.
> 
> Signed-off-by: Akhil R <akhilrajeev@...dia.com>
> ---
>   drivers/dma/tegra186-gpc-dma.c | 37 +++++++++++++++++++++++++++-------
>   1 file changed, 30 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/dma/tegra186-gpc-dma.c b/drivers/dma/tegra186-gpc-dma.c
> index fa9bda4a2bc6..1d1180db6d4e 100644
> --- a/drivers/dma/tegra186-gpc-dma.c
> +++ b/drivers/dma/tegra186-gpc-dma.c
> @@ -161,7 +161,10 @@
>   #define TEGRA_GPCDMA_BURST_COMPLETION_TIMEOUT	5000 /* 5 msec */
>   
>   /* Channel base address offset from GPCDMA base address */
> -#define TEGRA_GPCDMA_CHANNEL_BASE_ADD_OFFSET	0x20000
> +#define TEGRA_GPCDMA_CHANNEL_BASE_ADDR_OFFSET	0x10000

Why did this value change? There is no mention in the commit message. If 
this was incorrect before, then this needs to be a separate patch and 
tagged with the appropriate fixes tag so that this can be picked up for 
stable.

Thanks
Jon

-- 
nvpublic