linux-kernel - Re: Re: [PATCH v13 2/8] mtd: rawnand: rockchip: NFC drivers for RK3308, RK2928 and others

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Date:   Mon, 2 Nov 2020 16:14:01 +0800
From:   赵仪峰 <yifeng.zhao@...k-chips.com>
To:     "Miquel Raynal" <miquel.raynal@...tlin.com>
Cc:     "Johan Jonker" <jbx6244@...il.com>, richard <richard@....at>,
        vigneshr <vigneshr@...com>, robh+dt <robh+dt@...nel.org>,
        devicetree <devicetree@...r.kernel.org>,
        HeikoStübner <heiko@...ech.de>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-rockchip <linux-rockchip@...ts.infradead.org>,
        linux-mtd <linux-mtd@...ts.infradead.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>
Subject: Re: Re: [PATCH v13 2/8] mtd: rawnand: rockchip: NFC drivers for RK3308, RK2928 and others

Hi Miquel,

The nand_base.c will call nand_deselect_target after NAND read/program... ops done, and set variable chip->cur_cs = -1,
but the nand controller do nothing and the cs of the NAND device is still selected, 
so the NAND device  will not enter auto power save mode.

--------------
Thanks,
Yifeng

>Hello,
>
>赵仪峰 <yifeng.zhao@...k-chips.com> wrote on Mon, 2 Nov 2020 11:46:04
>+0800:
>
>> Hi Johan,
>>
>> void nand_deselect_target(struct nand_chip *chip)
>> {
>> if (chip->legacy.select_chip)
>> chip->legacy.select_chip(chip, -1);
>>
>> chip->cur_cs = -1;
>> }
>>
>> I need add the code below and it work.
>>
>>    chip->legacy.select_chip = rk_nfc_select_chip;
>>
>> But I found almost all nandc drivers do not add this code. Is there any other way to implement it？
>
>Indeed, we don't accept new code we legacy bindings.
>
>I don't understand what extra consumption you are trying to avoid,
>because if it is the NAND device itself that is able to save power when
>it gets unselected, it's really none of you controller's business.
>
>Perhaps it's the time to focus on the controller support and tune the
>code base later in a bid to reduce consumption.
>
>Thanks,
>Miquèl
>
>
>