linux-kernel - Re: [PATCH 5/5] i2c: designware: Switch over to i2c_freq_mode

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Message-ID: <YGRMrMI2ADSV9RBa@smile.fi.intel.com>
Date:   Wed, 31 Mar 2021 13:19:24 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     "Song Bao Hua (Barry Song)" <song.bao.hua@...ilicon.com>
Cc:     yangyicong <yangyicong@...wei.com>,
        "wsa@...nel.org" <wsa@...nel.org>,
        "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
        "Sergey.Semin@...kalelectronics.ru" 
        <Sergey.Semin@...kalelectronics.ru>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "digetx@...il.com" <digetx@...il.com>,
        "treding@...dia.com" <treding@...dia.com>,
        "jarkko.nikula@...ux.intel.com" <jarkko.nikula@...ux.intel.com>,
        "rmk+kernel@...linux.org.uk" <rmk+kernel@...linux.org.uk>,
        John Garry <john.garry@...wei.com>,
        "mika.westerberg@...ux.intel.com" <mika.westerberg@...ux.intel.com>,
        "Zengtao (B)" <prime.zeng@...ilicon.com>,
        Linuxarm <linuxarm@...wei.com>
Subject: Re: [PATCH 5/5] i2c: designware: Switch over to
 i2c_freq_mode_string()

On Wed, Mar 31, 2021 at 08:53:02AM +0000, Song Bao Hua (Barry Song) wrote:
> 
> > No, please read the code carefully.
> > We can duplicate conditional, but it brings a bit of inconsistency to how the counters are printed.
> 
> Thanks for clarification, I am still confused as the original
> code print the real mode based on dev->master_cfg, the new
> code is printing mode based on frequency.
> 
> My understanding is the original code could fall back to a lower
> speed when higher speed modes were not set successfully. For
> example, high speed mode falls back to fast mode:

This is a good catch! I should be fixed by a separate patch I assume.

> if ((dev->master_cfg & DW_IC_CON_SPEED_MASK) ==
> 		DW_IC_CON_SPEED_HIGH) {
> 		if ((comp_param1 & DW_IC_COMP_PARAM_1_SPEED_MODE_MASK)
> 			!= DW_IC_COMP_PARAM_1_SPEED_MODE_HIGH) {
> 			dev_err(dev->dev, "High Speed not supported!\n");
> 			dev->master_cfg &= ~DW_IC_CON_SPEED_MASK;
> 			dev->master_cfg |= DW_IC_CON_SPEED_FAST;

Basically we have to adjust timings here to reflect this change.

> 			dev->hs_hcnt = 0;
> 			dev->hs_lcnt = 0;
> 		}


-- 
With Best Regards,
Andy Shevchenko