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Subject: Re: [PATCH] lib: scatterlist: Fix to support no mapped sg
To:     Robert Jarzmik <robert.jarzmik@free.fr>
References: <1555581006-153458-1-git-send-email-wangzhou1@hisilicon.com>
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        <linuxarm@huawei.com>
From:   Zhou Wang <wangzhou1@hisilicon.com>
Message-ID: <5CBA967C.5010502@hisilicon.com>
Date:   Sat, 20 Apr 2019 11:48:12 +0800
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On 2019/4/19 18:43, Robert Jarzmik wrote:
> Zhou Wang <wangzhou1@hisilicon.com> writes:
> 
>> In function sg_split, the second sg_calculate_split will return -EINVAL
>> when in_mapped_nents is 0.
>>
>> Indeed there is no need to do second sg_calculate_split and sg_split_mapped
>> when in_mapped_nents is 0, as in_mapped_nents indicates no mapped entry in
>> original sgl.
>>
>> Signed-off-by: Zhou Wang <wangzhou1@hisilicon.com>
> That's right. May I know what is the usecase which led you to this fix ?

I posted a patchset to support HiSilicon compression engine:
https://lkml.org/lkml/2019/1/23/358. As Herber Xu suggested, it should use
new crypto acomp API which uses sgl as data input and output. However, our
hardware can not handle compress head for input/output data, so I need split
input/output sgl firstly which is not mapped sgl.

New version of HiSilicon compression engine driver has not been posted to
community yet. I will do this later.

> 
> Acked-by: Robert Jarzmik <robert.jarzmik@free.fr>

Many thanks for your review,
Zhou

> 
> --
> Robert
> 
> .
>