linux-kernel - Re: [PATCH v2 2/2] dmaengine: sprd: Add Spreadtrum DMA configuration

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Message-ID: <CAMz4kuLXCB9RipP6zicc6efMaKWHycGFwsbMZNiQDAobsUCpvw@mail.gmail.com>
Date:   Fri, 11 May 2018 19:58:39 +0800
From:   Baolin Wang <baolin.wang@...aro.org>
To:     Vinod Koul <vkoul@...nel.org>
Cc:     Dan Williams <dan.j.williams@...el.com>,
        Eric Long <eric.long@...eadtrum.com>,
        Mark Brown <broonie@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        dmaengine@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/2] dmaengine: sprd: Add Spreadtrum DMA configuration

On 11 May 2018 at 19:53, Vinod Koul <vkoul@...nel.org> wrote:
> On 11-05-18, 19:44, Baolin Wang wrote:
>> Hi Vinod,
>>
>> On 11 May 2018 at 19:22, Vinod Koul <vkoul@...nel.org> wrote:
>> > On 09-05-18, 19:12, Baolin Wang wrote:
>> >
>> >> +/*
>> >> + * struct sprd_dma_config - DMA configuration structure
>> >> + * @cfg: dma slave channel runtime config
>> >> + * @src_addr: the source physical address
>> >> + * @dst_addr: the destination physical address
>> >> + * @block_len: specify one block transfer length
>> >> + * @transcation_len: specify one transcation transfer length
>> >> + * @src_step: source transfer step
>> >> + * @dst_step: destination transfer step
>> >> + * @wrap_ptr: wrap pointer address, once the transfer address reaches the
>> >> + * 'wrap_ptr', the next transfer address will jump to the 'wrap_to' address.
>> >> + * @wrap_to: wrap jump to address
>> >> + * @req_mode: specify the DMA request mode
>> >> + * @int_mode: specify the DMA interrupt type
>> >> + */
>> >> +struct sprd_dma_config {
>> >> +     struct dma_slave_config cfg;
>> >> +     phys_addr_t src_addr;
>> >> +     phys_addr_t dst_addr;
>> >
>> > these are already in cfg so why duplicate, same for few more here.
>>
>> We save them in 'struct sprd_dma_config' as one parameter for
>> sprd_dma_config(), otherwise we need add 2 more parameters (src and
>> dst) for sprd_dma_config().
>
> I am not sure I follow...
>
> I meant you can use sprd_dma_config.cfg->src_addr/dst_addr and remove src_addr &
> dst_addr in the sprd_dma_config. It duplicate..

But we can not set values if dir == DMA_MEM_TO_DEV, since they
represent the device address, right?
sprd_dma_config.cfg->src_addr = sg_dma_address(sg);

>
> Same for few more params...
>
>> >> +     if (!is_slave_direction(dir) || sglen > 1)
>> >> +             return NULL;
>> >> +
>> >> +     sdesc = kzalloc(sizeof(*sdesc), GFP_NOWAIT);
>> >> +     if (!sdesc)
>> >> +             return NULL;
>> >> +
>> >> +     for_each_sg(sgl, sg, sglen, i) {
>> >> +             if (dir == DMA_MEM_TO_DEV) {
>> >> +                     slave_cfg->src_addr = sg_dma_address(sg);
>> >> +                     slave_cfg->dst_addr = slave_cfg->cfg.dst_addr;
>> >> +                     slave_cfg->src_step =
>> >> +                     sprd_dma_get_step(slave_cfg->cfg.src_addr_width);
>> >> +                     slave_cfg->dst_step = SPRD_DMA_NONE_STEP;
>> >> +             } else {
>> >> +                     slave_cfg->src_addr = slave_cfg->cfg.src_addr;
>> >> +                     slave_cfg->dst_addr = sg_dma_address(sg);
>> >> +                     slave_cfg->src_step = SPRD_DMA_NONE_STEP;
>> >> +                     slave_cfg->dst_step =
>> >> +                     sprd_dma_get_step(slave_cfg->cfg.dst_addr_width);
>> >
>> > use a helper for filling this and passing right values for each case?
>>
>> We need pass many values to this helper, but will try. Thanks.
>
> I think 5 and that may help to look it better :)

OK.

-- 
Baolin.wang
Best Regards