linux-kernel - Re: [PATCH v3 03/16] spi: dw: Discard static DW DMA slave structures

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Date:   Thu, 21 May 2020 12:57:17 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Serge Semin <Sergey.Semin@...kalelectronics.ru>
Cc:     Mark Brown <broonie@...nel.org>,
        Serge Semin <fancer.lancer@...il.com>,
        Georgy Vlasov <Georgy.Vlasov@...kalelectronics.ru>,
        Ramil Zaripov <Ramil.Zaripov@...kalelectronics.ru>,
        Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Paul Burton <paulburton@...nel.org>,
        Ralf Baechle <ralf@...ux-mips.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Arnd Bergmann <arnd@...db.de>,
        Rob Herring <robh+dt@...nel.org>, linux-mips@...r.kernel.org,
        devicetree <devicetree@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Wan Ahmad Zainie <wan.ahmad.zainie.wan.mohamad@...el.com>,
        Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
        Clement Leger <cleger@...ray.eu>,
        linux-spi <linux-spi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 03/16] spi: dw: Discard static DW DMA slave structures

On Thu, May 21, 2020 at 4:23 AM Serge Semin
<Sergey.Semin@...kalelectronics.ru> wrote:
>
> Having them declared is redundant since each struct dw_dma_chan has
> the same structure embedded and the structure from the passed dma_chan
> private pointer will be copied there as a result of the next calls
> chain:
> dma_request_channel() -> find_candidate() -> dma_chan_get() ->
> device_alloc_chan_resources() = dwc_alloc_chan_resources() ->
> dw_dma_filter().
> So just remove the static dw_dma_chan structures and use a locally
> declared data instance with dst_id/src_id set to the same values as
> the static copies used to have.

...

> - Explicitly initialize the dw_dma_slave members on stack.

Thanks for an update, but that's not what I asked for...

> -static struct dw_dma_slave mid_dma_tx = { .dst_id = 1 };
> -static struct dw_dma_slave mid_dma_rx = { .src_id = 0 };

>  static int mid_spi_dma_init_mfld(struct device *dev, struct dw_spi *dws)
>  {
> +       struct dw_dma_slave slave = {
> +               .src_id = 0,
> +               .dst_id = 0
> +       };

(It's member, and not memberS)

> -       struct dw_dma_slave *tx = dws->dma_tx;
> -       struct dw_dma_slave *rx = dws->dma_rx;

May we simple do

struct dw_dma_slave tx = { .dst_id = 1 };
struct dw_dma_slave rx = { .src_id = 0 };

please?

-- 
With Best Regards,
Andy Shevchenko