On Wed, 8 May 2019 13:59:14 +0000
Peng Fan <peng....@nxp.com> wrote:

> > -----Original Message-----
> > From: Lukasz Majewski [mailto:lu...@denx.de]
> > Sent: 2019年5月8日 14:38
> > To: Peng Fan <peng....@nxp.com>
> > Cc: u-boot@lists.denx.de; Tom Rini <tr...@konsulko.com>; Marcel
> > Ziswiler <marcel.ziswi...@toradex.com>; Fabio Estevam
> > <fabio.este...@nxp.com>; dl-uboot-imx <uboot-...@nxp.com>;
> > sba...@denx.de; Stefan Agner <stefan.ag...@toradex.com>; BOUGH CHEN
> > <haibo.c...@nxp.com>; Ye Li <ye...@nxp.com>
> > Subject: Re: [PATCH] Revert "mmc: fsl_esdhc: fix sd/mmc ddr mode
> > clock setting issue"
> > 
> > On Wed, 8 May 2019 08:19:45 +0200
> > Lukasz Majewski <lu...@denx.de> wrote:
> >   
> > > Hi Peng,
> > >  
> > > > Hi Lukasz,
> > > >  
> > > > > Subject: [PATCH] Revert "mmc: fsl_esdhc: fix sd/mmc ddr mode
> > > > > clock setting issue"
> > > > >
> > > > > This reverts commit 72a89e0da5ac6a4ab929b15a2b656f04f50767f6,
> > > > > which causes the imx53 HSC to hang as the eMMC is not working
> > > > > properly anymore.
> > > > >
> > > > > The exact error message:
> > > > > MMC write: dev # 0, block # 2, count 927 ... mmc write failed
> > > > > 0 blocks written: ERROR
> > > > >
> > > > > imx53 is not using the DDR mode.
> > > > >
> > > > > Debugging of pre_div and div generation showed that those
> > > > > values are generated in a way, which is not matching the ones
> > > > > from working setup.
> > > > >
> > > > > As the original patch was performing code refactoring, let's
> > > > > revert this change, so all imx53 boards would work again.  
> > > >
> > > > Could you share what is the clock value for your board?  
> > >
> > > Sure, no problem:
> > >
> > > Working setup:
> > > --------------
> > >
> > > MMC:
> > > set_sysctl: pre_div = 2 mmc->ddr: 0 sdhc_clk: 80000000
> > >  pre_div: 8 div: 12 set_sysctl: clk: 2240
> > > FSL_SDHC: 0
> > > Loading Environment from MMC...
> > > set_sysctl: pre_div = 2 mmc->ddr: 0 sdhc_clk: 80000000
> > >  pre_div: 8 div: 12 set_sysctl: clk: 2240
> > >
> > > set_sysctl: pre_div = 2 mmc->ddr: 0 sdhc_clk: 80000000
> > >  pre_div: 8 div: 12 set_sysctl: clk: 2240
> > >
> > > set_sysctl: pre_div = 2 mmc->ddr: 0 sdhc_clk: 80000000
> > >  pre_div: 1 div: 1 set_sysctl: clk: 272
> > >
> > > set_sysctl: pre_div = 2 mmc->ddr: 0 sdhc_clk: 80000000
> > >  pre_div: 1 div: 0 set_sysctl: clk: 256
> > >
> > >
> > >
> > >
> > > Broken:
> > > -------
> > > MMC:
> > > set_sysctl: pre_div = 2 mmc->ddr: 0 sdhc_clk: 80000000
> > >  pre_div: 8 div: 12 set_sysctl: clk: 2240
> > > FSL_SDHC: 0
> > > Loading Environment from MMC...
> > > set_sysctl: pre_div = 2 mmc->ddr: 0 sdhc_clk: 80000000
> > >  pre_div: 8 div: 12 set_sysctl: clk: 2240
> > >
> > > set_sysctl: pre_div = 2 mmc->ddr: 0 sdhc_clk: 80000000
> > >  pre_div: 8 div: 12 set_sysctl: clk: 2240
> > >
> > > set_sysctl: pre_div = 2 mmc->ddr: 0 sdhc_clk: 80000000
> > >  pre_div: 0 div: 3 set_sysctl: clk: 48
> > >
> > > set_sysctl: pre_div = 2 mmc->ddr: 0 sdhc_clk: 80000000
> > >  pre_div: 0 div: 1 set_sysctl: clk: 16
> > >
> > >
> > > (Please also find attached patch to reproduce debug output).
> > >  
> > 
> > And maybe the most important question - why it was necessary to
> > refactor this code?
> > 
> > Parts responsible for calculating pre_div and div seems not related
> > to ddr problem (one spot issue is div <= 16 , but in the original
> > code it was div < 16)?  
> 
> Could you help verify whether the patch fixes you issue?
> 
> index 1b7de74a72..3347fbe738 100644
> --- a/drivers/mmc/fsl_esdhc.c
> +++ b/drivers/mmc/fsl_esdhc.c
> @@ -640,8 +640,7 @@ static void set_sysctl(struct fsl_esdhc_priv
> *priv, struct mmc *mmc, uint clock) for (; pre_div < 256; pre_div *=
> 2) if ((sdhc_clk / pre_div) <= (clock * 16))
>                                 break;
> -       } else
> -               pre_div = 1;
> +       }

Please examine this code thoroughly and provide patch.

The 
} else
        pre_div = 1;

was added there for a purpose, so I'm wondering why it can be easily
removed now.

> 
>         for (div = 1; div <= 16; div++)
>                 if ((sdhc_clk / (div * pre_div)) <= clock)
> 

As I've stated above - is the above for() correct?

In the original code it was div < 16, but here it is div <= 16.

> 
> Thanks,
> Peng.
> 
> >   
> > > >
> > > > Thanks,
> > > > Peng.
> > > >  
> > > > >
> > > > > Signed-off-by: Lukasz Majewski <lu...@denx.de>
> > > > > ---
> > > > >  drivers/mmc/fsl_esdhc.c | 23 +++++------------------
> > > > >  1 file changed, 5 insertions(+), 18 deletions(-)
> > > > >
> > > > > diff --git a/drivers/mmc/fsl_esdhc.c b/drivers/mmc/fsl_esdhc.c
> > > > > index 1b7de74a72..377b2673a3 100644
> > > > > --- a/drivers/mmc/fsl_esdhc.c
> > > > > +++ b/drivers/mmc/fsl_esdhc.c
> > > > > @@ -621,31 +621,18 @@ static void set_sysctl(struct
> > > > > fsl_esdhc_priv *priv, struct mmc *mmc, uint clock)  #else
> > > > >       int pre_div = 2;
> > > > >  #endif
> > > > > +     int ddr_pre_div = mmc->ddr_mode ? 2 : 1;
> > > > >       int sdhc_clk = priv->sdhc_clk;
> > > > >       uint clk;
> > > > >
> > > > > -     /*
> > > > > -      * For ddr mode, usdhc need to enable DDR mode first,
> > > > > after select
> > > > > -      * this DDR mode, usdhc will automatically divide the
> > > > > usdhc clock
> > > > > -      */
> > > > > -     if (mmc->ddr_mode) {
> > > > > -             writel(readl(&regs->mixctrl) |
> > > > > MIX_CTRL_DDREN, &regs->mixctrl);
> > > > > -             sdhc_clk >>= 1;
> > > > > -     }
> > > > > -
> > > > >       if (clock < mmc->cfg->f_min)
> > > > >               clock = mmc->cfg->f_min;
> > > > >
> > > > > -     if (sdhc_clk / 16 > clock) {
> > > > > -             for (; pre_div < 256; pre_div *= 2)
> > > > > -                     if ((sdhc_clk / pre_div) <= (clock *
> > > > > 16))
> > > > > -                             break;
> > > > > -     } else
> > > > > -             pre_div = 1;
> > > > > +     while (sdhc_clk / (16 * pre_div * ddr_pre_div) >
> > > > > clock && pre_div < 256)
> > > > > +             pre_div *= 2;
> > > > >
> > > > > -     for (div = 1; div <= 16; div++)
> > > > > -             if ((sdhc_clk / (div * pre_div)) <= clock)
> > > > > -                     break;
> > > > > +     while (sdhc_clk / (div * pre_div * ddr_pre_div) >
> > > > > clock && div < 16)
> > > > > +             div++;
> > > > >
> > > > >       pre_div >>= 1;
> > > > >       div -= 1;
> > > > > --
> > > > > 2.11.0  
> > > >  
> > >
> > >
> > >
> > >
> > > Best regards,
> > >
> > > Lukasz Majewski
> > >
> > > --
> > >
> > > DENX Software Engineering GmbH,      Managing Director: Wolfgang  
> > Denk  
> > > HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell,
> > > Germany Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email:
> > > lu...@denx.de  
> > 
> > 
> > 
> > 
> > Best regards,
> > 
> > Lukasz Majewski
> > 
> > --
> > 
> > DENX Software Engineering GmbH,      Managing Director: Wolfgang
> > Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell,
> > Germany Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email:
> > lu...@denx.de  




Best regards,

Lukasz Majewski

--

DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lu...@denx.de

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