linux-kernel - Re: [PATCH v4 1/2] mtd: rawnand: Add support for Macronix NAND randomizer

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Message-ID: <OF1377603E.0BE29BC1-ON482584F5.00335731-482584F5.00340DE4@mxic.com.tw>
Date:   Mon, 20 Jan 2020 17:28:35 +0800
From:   masonccyang@...c.com.tw
To:     "Miquel Raynal" <miquel.raynal@...tlin.com>
Cc:     bbrezillon@...nel.org, computersforpeace@...il.com,
        devicetree@...r.kernel.org, dwmw2@...radead.org,
        juliensu@...c.com.tw, linux-kernel@...r.kernel.org,
        linux-mtd@...ts.infradead.org, marek.vasut@...il.com,
        mark.rutland@....com, richard@....at, robh+dt@...nel.org,
        vigneshr@...com
Subject: Re: [PATCH v4 1/2] mtd: rawnand: Add support for Macronix NAND randomizer

Hi Miquel,

> > > > +}
> > > > +
> > > >  static void macronix_nand_onfi_init(struct nand_chip *chip)
> > > >  {
> > > >     struct nand_parameters *p = &chip->parameters;
> > > >     struct nand_onfi_vendor_macronix *mxic;
> > > > +   struct device_node *dn = nand_get_flash_node(chip);
> > > > +   int rand_otp = 0;
> > > > +   int ret;
> > > > 
> > > >     if (!p->onfi)
> > > >        return;
> > > > 
> > > > +   if (of_find_property(dn, "mxic,enable-randomizer-otp", NULL))
> > > > +      rand_otp = 1;
> > > > +
> > > >     mxic = (struct nand_onfi_vendor_macronix *)p->onfi->vendor;
> > > > +   /* Subpage write is prohibited in randomizer operatoin */ 
> > > 
> > >                                        with          operation
> > > 
> > > > +   if (rand_otp && chip->options & NAND_NO_SUBPAGE_WRITE &&
> > > > +       mxic->reliability_func & MACRONIX_RANDOMIZER_BIT) {
> > > > +      if (p->supports_set_get_features) {
> > > > +         bitmap_set(p->set_feature_list,
> > > > +               ONFI_FEATURE_ADDR_MXIC_RANDOMIZER, 1);
> > > > +         bitmap_set(p->get_feature_list,
> > > > +               ONFI_FEATURE_ADDR_MXIC_RANDOMIZER, 1);
> > > > +         ret = macronix_nand_randomizer_check_enable(chip);
> > > > +         if (ret < 0)
> > > > +            pr_info("Macronix NAND randomizer failed\n");
> > > > +         else
> > > > +            pr_info("Macronix NAND randomizer enabled\n"); 
> > > 
> > > Maybe we should update the bitmaps only if it succeeds? 
> > 
> > okay, will drop pr_info();
> 
> It's not my point, you can keep the pr_info, I just say that you should
> check ret before updating the bitmap maybe? Otherwise if
> macronix_nand_randomizer_check_enable() fails, you end up without the
> feature but with its bit set in the bitmap.

Driver should set ONFI_FEATURE_ADDR_MXIC_RANDOMIZER in 
p->set/get_feature_list
before calling macronix_nand_randomizer_check_enable() for randomizer 
set/get
feature operation.

I will patch bitmap_clear() if macronix_nand_randomizer_check_enable() 
return fails.

thanks for your time & comments.
Mason

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