linux-kernel - Re: [PATCH V7 5/5] mmc: host: sdhci-pci: Add Genesys Logic GL975x support

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Date:   Wed, 4 Sep 2019 08:58:19 +0800
From:   Ben Chuang <benchuanggli@...il.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Adrian Hunter <adrian.hunter@...el.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        linux-mmc <linux-mmc@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "Michael K. Johnson" <johnsonm@...lj.org>,
        Ben Chuang <ben.chuang@...esyslogic.com.tw>
Subject: Re: [PATCH V7 5/5] mmc: host: sdhci-pci: Add Genesys Logic GL975x support

On Tue, Sep 3, 2019 at 6:05 AM Andy Shevchenko
<andy.shevchenko@...il.com> wrote:
>
> On Fri, Aug 30, 2019 at 5:28 AM Ben Chuang <benchuanggli@...il.com> wrote:
> >
> > From: Ben Chuang <ben.chuang@...esyslogic.com.tw>
> >
> > Add support for the GL9750 and GL9755 chipsets.
> >
> > Enable v4 mode and wait 5ms after set 1.8V signal enable for GL9750/
> > GL9755. Fix the value of SDHCI_MAX_CURRENT register and use the vendor
> > tuning flow for GL9750.
> >
>
> > Signed-off-by: Ben Chuang <ben.chuang@...esyslogic.com.tw>
>
> Usually last one for latest developer / submitter goes on.
>
> > Co-developed-by: Michael K Johnson <johnsonm@...lj.org>
> > Signed-off-by: Michael K Johnson <johnsonm@...lj.org>
>
>
> > +#define GLI_MAX_TUNING_LOOP 40
>
>
> > +static void gli_set_9750(struct sdhci_host *host)
> > +{
> > +       u32 driving_value = 0;
> > +       u32 pll_value = 0;
> > +       u32 sw_ctrl_value = 0;
> > +       u32 misc_value = 0;
> > +       u32 parameter_value = 0;
> > +       u32 control_value = 0;
>
> > +
>
> Redundant blank line.
>
> > +       u16 ctrl2 = 0;
>
> Do you need these all assignments above?
>
> > +       driving_value = sdhci_readl(host, SDHCI_GLI_9750_DRIVING);
> > +       pll_value = sdhci_readl(host, SDHCI_GLI_9750_PLL);
> > +       sw_ctrl_value = sdhci_readl(host, SDHCI_GLI_9750_SW_CTRL);
> > +       misc_value = sdhci_readl(host, SDHCI_GLI_9750_MISC);
> > +       parameter_value = sdhci_readl(host, SDHCI_GLI_9750_TUNING_PARAMETERS);
> > +       control_value = sdhci_readl(host, SDHCI_GLI_9750_TUNING_CONTROL);
>
>
>
> > +
> > +       udelay(1);
>
> This misses the answer to question why. Why this is needed and why
> timeout is this long?
>
> > +
> > +       gl9750_wt_off(host);
> > +}
>
> > +static int __sdhci_execute_tuning_9750(struct sdhci_host *host, u32 opcode)
> > +{
> > +       int i;
>
> > +       int rx_inv = 0;
>
> Duplicate assignment.
>
> > +
> > +       for (rx_inv = 0; rx_inv < 2; rx_inv++) {
>
> > +               if (rx_inv & 0x1)
> > +                       gli_set_9750_rx_inv(host, true);
> > +               else
> > +                       gli_set_9750_rx_inv(host, false);
>
> gli_set_...(host, !!rx_inv);
>
> > +
> > +               sdhci_start_tuning(host);
> > +
> > +               for (i = 0; i < GLI_MAX_TUNING_LOOP; i++) {
> > +                       u16 ctrl;
> > +
> > +                       sdhci_send_tuning(host, opcode);
> > +
> > +                       if (!host->tuning_done) {
>
> > +                               if (rx_inv == 1) {
>
> It's an invariant to the loop. So, you may do this check after outter loop.
>
> > +                                       pr_info("%s: Tuning timeout, falling back to fixed sampling clock\n",
> > +                                               mmc_hostname(host->mmc));
>
> > +                                       sdhci_abort_tuning(host, opcode);
>
> It will also de-duplicates this call.
>
> > +                                       return -ETIMEDOUT;
> > +                               }
> > +                               sdhci_abort_tuning(host, opcode);
> > +                               break;
> > +                       }
>
> > +               }
> > +       }
> > +
> > +       pr_info("%s: Tuning failed, falling back to fixed sampling clock\n",
> > +               mmc_hostname(host->mmc));
> > +       sdhci_reset_tuning(host);
> > +       return -EAGAIN;
> > +}
>
> > +static void sdhci_gli_voltage_switch(struct sdhci_host *host)
> > +{
>
> Any comment why?
>
> > +       usleep_range(5000, 5500);
> > +}
>
> > +static u32 sdhci_gl9750_readl(struct sdhci_host *host, int reg)
> > +{
> > +       u32 value;
> > +
> > +       value = readl(host->ioaddr + reg);
>
> > +       if (unlikely(reg == SDHCI_MAX_CURRENT)) {
> > +               if (!(value & 0xff))
> > +                       value |= 0xc8;
> > +       }
>
> if (a) {
>  if (b) {
>    ...
>  }
> }
>
> is the same as
>
> if (a && b) {
>  ...
> }
>
> > +       return value;
> > +}
>
> > +#define PCI_DEVICE_ID_GLI_9755         0x9755
> > +#define PCI_DEVICE_ID_GLI_9750         0x9750
>
> --
> With Best Regards,
> Andy Shevchenko

Hi, Andy,

Thank you for your comments to make the code better.
Waiting to see if Adrian has any other comments.

Best Regards,
Ben Chuang