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From: John Watts <contact@jookia.org>
To: Sascha Hauer <sha@pengutronix.de>
Cc: barebox@lists.infradead.org
Subject: Re: [PATCH] I2C: i.MX: early: Use internal udelay
Date: Mon, 30 Jan 2023 23:24:55 +1100	[thread overview]
Message-ID: <Y9e3F2WtTDWOhbE0@novena-choice-citizen> (raw)
In-Reply-To: <20230130121752.GR13319@pengutronix.de>

On Mon, Jan 30, 2023 at 01:17:52PM +0100, Sascha Hauer wrote:
> On Mon, Jan 30, 2023 at 09:42:53PM +1100, John Watts wrote:
> > On Mon, Jan 30, 2023 at 11:27:27AM +0100, Sascha Hauer wrote:
> > > This takes around 5 times too long on a i.MX8MM and around 50 times too
> > > long on a i.MX6Q. This was measured under a regular barebox on the
> > > shell. In an early environment with MMU disabled it takes 730 times too
> > > long.
> > 
> > Yikes! I'm glad I broke this in to its own patch then. :)
> > 
> > I did copy this code from these boards:
> > 
> > arch/arm/boards/cm-fx6/lowlevel.c
> > arch/arm/boards/skov-imx6/lowlevel.c
> > arch/arm/boards/technexion-wandboard/lowlevel.c
> > arch/arm/mach-imx/xload-gpmi-nand.c
> > arch/arm/mach-imx/imx6-mmdc.c (uses 1000 loops)
> > 
> > Maybe it's time for an i.MX6-wide early udelay?
> 
> i.MX6 is not enough, the code could run on other i.MX SoCs as well.

Do you think a patch that implements udelay in PBL using the code below with
a fixed base and drops these implementations would be a good idea?

> I tested this with a call to this udelay function with a sufficiently
> great number of microseconds surrounded by a printf.

Ah okay.

> I briefly looked into this, but the commit history of both barebox or
> Linux do not give a real conclusion what we are waiting here for.
> 
> Sascha

I see.

John.



  reply	other threads:[~2023-01-30 18:21 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-26 18:56 John Watts
2023-01-30 10:27 ` Sascha Hauer
2023-01-30 10:42   ` John Watts
2023-01-30 12:17     ` Sascha Hauer
2023-01-30 12:24       ` John Watts [this message]
2023-01-30 12:31         ` Sascha Hauer
2023-01-30 12:56           ` John Watts
2023-01-30 16:36             ` Sascha Hauer
2023-01-30 18:42               ` John Watts
2023-01-31  6:14                 ` Sascha Hauer
2023-01-31  6:33                   ` John Watts
2023-02-02 14:21   ` Jules Maselbas
2023-02-02 14:27     ` Ahmad Fatoum
2023-02-01 17:50 ` Alexander Shiyan
2023-02-01 18:12   ` Jookia
2023-02-01 19:44   ` Ahmad Fatoum

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