linux-kernel - Re: [PATCH] habanalabs: Remove unused enum member DMA_SRAM_TO

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Message-ID: <CAFCwf10GWN_hdsvUf+7dFFK=CwjuGxXPZZt8c2dkVOb24VZxcQ@mail.gmail.com>
Date:   Sun, 23 Jan 2022 16:43:15 +0200
From:   Oded Gabbay <ogabbay@...nel.org>
To:     Cai Huoqing <cai.huoqing@...ux.dev>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Linux-Kernel@...r. Kernel. Org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] habanalabs: Remove unused enum member DMA_SRAM_TO_SRAM

On Tue, Jan 11, 2022 at 1:47 PM Cai Huoqing <cai.huoqing@...ux.dev> wrote:
>
> The driver don't support the SRAM-to-SRAM translation of DMA,
> so remove 'DMA_SRAM_TO_SRAM'.
>
> Signed-off-by: Cai Huoqing <cai.huoqing@...ux.dev>
> ---
>  drivers/misc/habanalabs/include/goya/goya_packets.h | 1 -
>  1 file changed, 1 deletion(-)
>
> diff --git a/drivers/misc/habanalabs/include/goya/goya_packets.h b/drivers/misc/habanalabs/include/goya/goya_packets.h
> index ef54bad20509..25fbebdc6143 100644
> --- a/drivers/misc/habanalabs/include/goya/goya_packets.h
> +++ b/drivers/misc/habanalabs/include/goya/goya_packets.h
> @@ -36,7 +36,6 @@ enum goya_dma_direction {
>         DMA_SRAM_TO_HOST,
>         DMA_DRAM_TO_HOST,
>         DMA_DRAM_TO_DRAM,
> -       DMA_SRAM_TO_SRAM,
>         DMA_ENUM_MAX
>  };
>
> --
> 2.25.1
>

This is a general spec file in our s/w stack, and therefore a change
in it in the driver will cause our driver to be out of sync with our
user-space stack. i.e. the value of DMA_ENUM_MAX will be different in
the driver and in the user-space stack. I don't know if there will be
any consequences but I prefer not to risk it.

In addition, I prefer to have this value present for completeness,
even if the driver doesn't refer to it.

Oded