linux-kernel - Re: [PATCH] mmc: sdhci: use lower/upper_32

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Date:   Thu, 29 Aug 2019 20:25:52 +0900
From:   Masahiro Yamada <yamada.masahiro@...ionext.com>
To:     Adrian Hunter <adrian.hunter@...el.com>
Cc:     linux-mmc <linux-mmc@...r.kernel.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mmc: sdhci: use lower/upper_32_bits() macros for DMA addresses

Hi.

On Wed, Aug 28, 2019 at 10:02 PM Adrian Hunter <adrian.hunter@...el.com> wrote:
>
> On 28/08/19 2:14 PM, Masahiro Yamada wrote:
> > Currently, the DMA addresses are casted to (u64) for the upper 32bits
> > to avoid "right shift count >= width of type" warning.
> >
> > <linux/kernel.h> provides macros to address this, and the macro names
> > are self-documenting.
> >
> > Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>
> > ---
> >
> >  drivers/mmc/host/sdhci.c | 14 ++++++++------
> >  1 file changed, 8 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> > index a5dc5aae973e..07144a195a9f 100644
> > --- a/drivers/mmc/host/sdhci.c
> > +++ b/drivers/mmc/host/sdhci.c
> > @@ -668,10 +668,10 @@ void sdhci_adma_write_desc(struct sdhci_host *host, void **desc,
> >       /* 32-bit and 64-bit descriptors have these members in same position */
> >       dma_desc->cmd = cpu_to_le16(cmd);
> >       dma_desc->len = cpu_to_le16(len);
> > -     dma_desc->addr_lo = cpu_to_le32((u32)addr);
> > +     dma_desc->addr_lo = cpu_to_le32(lower_32_bits(addr));
> >
> >       if (host->flags & SDHCI_USE_64_BIT_DMA)
> > -             dma_desc->addr_hi = cpu_to_le32((u64)addr >> 32);
> > +             dma_desc->addr_hi = cpu_to_le32(upper_32_bits(addr));
> >
> >       *desc += host->desc_sz;
> >  }
> > @@ -827,9 +827,10 @@ static dma_addr_t sdhci_sdma_address(struct sdhci_host *host)
> >  static void sdhci_set_sdma_addr(struct sdhci_host *host, dma_addr_t addr)
> >  {
> >       if (host->v4_mode) {
>
> To reduce line wrapping, how about using:
>
>                 u32 lo = lower_32_bits(addr);
>                 u32 hi = upper_32_bits(addr);
>
> > -             sdhci_writel(host, addr, SDHCI_ADMA_ADDRESS);
> > +             sdhci_writel(host, lower_32_bits(addr), SDHCI_ADMA_ADDRESS);
> >               if (host->flags & SDHCI_USE_64_BIT_DMA)
> > -                     sdhci_writel(host, (u64)addr >> 32, SDHCI_ADMA_ADDRESS_HI);
> > +                     sdhci_writel(host, upper_32_bits(addr),
> > +                                  SDHCI_ADMA_ADDRESS_HI);
> >       } else {
> >               sdhci_writel(host, addr, SDHCI_DMA_ADDRESS);
> >       }
> > @@ -1096,10 +1097,11 @@ static void sdhci_prepare_data(struct sdhci_host *host, struct mmc_command *cmd)
> >               } else if (host->flags & SDHCI_USE_ADMA) {
>
> To reduce line wrapping, how about using:
>
>                         u32 lo = lower_32_bits(host->adma_addr);
>                         u32 hi = upper_32_bits(host->adma_addr);
>
> >                       sdhci_adma_table_pre(host, data, sg_cnt);
> >
> > -                     sdhci_writel(host, host->adma_addr, SDHCI_ADMA_ADDRESS);
> > +                     sdhci_writel(host, lower_32_bits(host->adma_addr),
> > +                                  SDHCI_ADMA_ADDRESS);
> >                       if (host->flags & SDHCI_USE_64_BIT_DMA)
> >                               sdhci_writel(host,
> > -                                          (u64)host->adma_addr >> 32,
> > +                                          upper_32_bits(host->adma_addr),
> >                                            SDHCI_ADMA_ADDRESS_HI);
> >               } else {
> >                       WARN_ON(sg_cnt != 1);
> >
>


I used another way to reduce the line wrapping in v2.
I factored out the duplicated code into a new helper,
sdhci_set_adma_addr().

If you do not like it, I will adopt your suggestion,
but anyway take a look at v2.

-- 
Best Regards
Masahiro Yamada