On Mon, Apr 30, 2018 at 08:51:45AM +1000, NeilBrown wrote:
> On Sun, Apr 29 2018, Christian Lütke-Stetzkamp wrote:
> 
> > The function msdc_set_blknum consists of one (real) line of code and
> > is only called once, so inline it makes the code shorter and more
> > readable.
> >
> > Signed-off-by: Christian Lütke-Stetzkamp <christ...@lkamp.de>
> > ---
> >  drivers/staging/mt7621-mmc/sd.c | 10 +---------
> >  1 file changed, 1 insertion(+), 9 deletions(-)
> >
> > diff --git a/drivers/staging/mt7621-mmc/sd.c 
> > b/drivers/staging/mt7621-mmc/sd.c
> > index c9f0180f3220..00c862b02419 100644
> > --- a/drivers/staging/mt7621-mmc/sd.c
> > +++ b/drivers/staging/mt7621-mmc/sd.c
> > @@ -1182,14 +1182,6 @@ static void msdc_dma_setup(struct msdc_host *host, 
> > struct msdc_dma *dma,
> >     msdc_dma_config(host, dma);
> >  }
> >  
> > -/* set block number before send command */
> > -static void msdc_set_blknum(struct msdc_host *host, u32 blknum)
> > -{
> > -   void __iomem *base = host->base;
> > -
> > -   sdr_write32(SDC_BLK_NUM, blknum);
> > -}
> > -
> 
> This change is correct, but the reason isn't obvious.
> In mt6575_sd.h are:
> 
> #define SDC_BLK_NUM             REG_ADDR(SDC_BLK_NUM)
> 
> #define REG_ADDR(x)                 (base + OFFSET_##x)
> 
> So the above becomes
> 
>    sdr_write32((base + OFFSET_SDC_BLK_NUM), blknum);
> 
> so the base is important.
> 
> msdc_do_request() starts with
> 
>       void __iomem *base = host->base;
> 
> and never changes host.  So that "base" that is used in the new code is
> the same as the "base" used in the old code.
> 
> Ugh.. what a horrible way to write code!

Yes it is horrible and in a future cleanup I will remove all the
things depending on that "magic" base variable. But currently this is
the common (bad) idiom all over this driver and I would like to
address them all at once.
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