linux-kernel - Re: [RFC PATCH] mtd: rawnand: ams-delta: use ->exec

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Date:   Wed, 3 Oct 2018 16:06:34 +0200
From:   Boris Brezillon <boris.brezillon@...tlin.com>
To:     Janusz Krzysztofik <jmkrzyszt@...il.com>
Cc:     Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Marek Vasut <marek.vasut@...il.com>,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH] mtd: rawnand: ams-delta: use ->exec_op()

On Wed, 03 Oct 2018 15:55:25 +0200
Janusz Krzysztofik <jmkrzyszt@...il.com> wrote:
  
> > > 
> > > Implementation of NAND_OP_WAITRDY_INSTR has been based on legacy
> > > nand_wait_ready(),  
> > 
> > I don't remember what the ams-delta ->dev_ready()/->waitfunc() hooks
> > are doing, but is shouldn't be too hard to replace them by an
> > ams_delta_wait_ready() func.  
> 
> Default nand_wait() is used as ->waitfunc(), and ->dev_ready() returns R/B 
> GPIO pin status.

Okay. Then it might make sense to provide a generic helper to poll a
gpio.

void nand_gpio_waitrdy(struct nand_chip *chip, struct gpio_desc *gpiod)
{
	...
}

> 
> > > otherwise that function would probabaly have to be  
> > 
> > 				^ probably  
> 
> Do you think other drivers which now provide ->dev_ready() won't require 
> reimplementation of nand_wait_ready()?

It depends. I mean, most controllers support native R/B sensing, and in
case they do actually require you to poll the RB pin status, duplicating
the wait_ready() logic shouldn't be a problem. On the other hand, I
really want to get rid of ->dev_ready().