From: "René Bürgel" <r.buergel@unicontrol•de>
To: Wolfram Sang <w.sang@pengutronix•de>
Cc: linuxppc-dev@ozlabs•org
Subject: Re: [PATCH V2] workaround for mpc52xx erratum #364 (serial may not be reset in break state)
Date: Tue, 04 Nov 2008 15:13:55 +0100 [thread overview]
Message-ID: <491058A3.9040807@unicontrol.de> (raw)
In-Reply-To: <20081104111545.GB17864@pengutronix.de>
Wolfram Sang schrieb:
> Hello Rene,
>
> I haven't actually applied the patch, just a few comments from a
> glimpse:
>
> Major nit: Please add to the comment that this bug is still present on
> the MPC5200B, although it is not in its errata sheet. Thils will avoid
> later confusion. (Out of interest, did you contact Freescale about this
> bug?)
>
Comment added, contacting Freescale is still on my to-do-list :)
>
>> + *
>> + * The workaround resets the baudrate to 4800, waits for a stable state and resets break state repeatedly if necessary.
>> + * Optionally it can release the lock while waiting.
>> + * 1 character at 4800 baud takes 2ms, 3ms should be enough for 1 character at higher speed and 1 char at lowest
>> + * works only with longer delays
>>
>
> Did I get it right that there are cases where the workaround won't work?
>
Yes, currently it doesn't work when receiving with less than 4800 baud.
I'll try to fix this.
>
>> +{
>> + struct mpc52xx_psc __iomem *psc = PSC(port);
>> +#ifdef CONFIG_PPC_MPC52xx
>> + out_8(&psc->ctur,0x01);
>> + out_8(&psc->ctlr,0xae);
>>
>
> Those are magic values. If you can't build them using defined
> constants, at least document them, please.
>
The magic numbers will hopefully vanish after generalizing the patch to
work with every baudrate.
> Thanks!
>
> Wolfram Sang
>
>
Thanks for your suggestions
--
René Bürgel
Software Engineer
Unicontrol Systemtechnik GmbH
OT Dittersbach
Sachsenburger Weg 34
09669 Frankenberg
Tel.: 03 72 06/ 88 73 - 19
Fax: 03 72 06/ 88 73 - 60
E-Mail: r.buergel@unicontrol•de
Internet: www.unicontrol.de
Unicontrol Systemtechnik GmbH
Geschäftsführer: Dipl.-Ing. Siegfried Heinze
Sitz der Gesellschaft: Frankenberg
Registergericht: Amtsgericht Chemnitz, HRB 15 475
next prev parent reply other threads:[~2008-11-04 14:14 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-11-03 19:32 [PATCH] workaround for mpc52xx erratum #364 (serial may not be reset in break state) René Bürgel
2008-11-03 20:55 ` Grant Likely
2008-11-03 21:57 ` Matt Sealey
2008-11-03 22:15 ` Wolfram Sang
2008-11-03 22:55 ` Grant Likely
2008-11-04 18:18 ` Matt Sealey
2008-11-04 10:43 ` [PATCH V2] " René Bürgel
2008-11-04 11:15 ` Wolfram Sang
2008-11-04 14:13 ` René Bürgel [this message]
2008-11-04 19:40 ` [PATCH V3] " René Bürgel
2008-11-04 21:21 ` Wolfram Sang
2008-11-06 8:11 ` [PATCH V4] " René Bürgel
2008-11-14 19:09 ` Grant Likely
2008-11-04 18:23 ` [PATCH V2] " Matt Sealey
2008-11-06 17:01 ` René Bürgel
2008-11-06 22:41 ` Matt Sealey
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