From: Wolfram Sang <w.sang-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org> To: Marek Vasut <marex-ynQEQJNshbs@public.gmane.org> Cc: linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Fabio Estevam <festevam-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Shawn Guo <shawn.guo-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>, linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Subject: Re: possible MXS-i2c bug Date: Thu, 26 Apr 2012 13:42:01 +0200 [thread overview] Message-ID: <20120426114201.GC3548@pengutronix.de> (raw) In-Reply-To: <201204261326.29388.marex-ynQEQJNshbs@public.gmane.org> [-- Attachment #1: Type: text/plain, Size: 1562 bytes --] Hi Marek, you forgot the most important list, linux-i2c ;) > I recently tried mxs-i2c (on 3.4-rc4) with at24 eeprom, didn't work as expected. Yes, we had the same this week/last week. > Apparently, there might be some timing issue, when I put printk() into the at24 > driver eeprom write function, it "fixed" itself. Though, replacing the i2c > driver with i2c gpio also fixed the issue, so I suspect the i2c driver has some > flaw in it. Try removing the printk and use the module paramter "io_limit=24" for at24. Does this help? (Or bs<=24 with dd) > If noone has any fixes already, I'll debug this tonight or so. The write FIFO overflows, since it only can carry 8 words. There is currently no check for that. One solution would be to check the FIFO status and fill them as needed. This will probably require additional locking, so I think the proper solution would be to use DMA for transfers bigger than the write FIFO size (we would get MX23 support then, too). Sadly, we don't have DMA support yet and I don't have time to implement it. I am thinking if such transfers which would fail anyway, should currently be rejected or if the driver should depend on BROKEN or both. I am still undecided, though. Please also check the patch I sent yesterday, there is also another one coming after I get confirmation from a customer. Regards, Wolfram -- Pengutronix e.K. | Wolfram Sang | Industrial Linux Solutions | http://www.pengutronix.de/ | [-- Attachment #2: Digital signature --] [-- Type: application/pgp-signature, Size: 198 bytes --]
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From: w.sang@pengutronix.de (Wolfram Sang) To: linux-arm-kernel@lists.infradead.org Subject: possible MXS-i2c bug Date: Thu, 26 Apr 2012 13:42:01 +0200 [thread overview] Message-ID: <20120426114201.GC3548@pengutronix.de> (raw) In-Reply-To: <201204261326.29388.marex@denx.de> Hi Marek, you forgot the most important list, linux-i2c ;) > I recently tried mxs-i2c (on 3.4-rc4) with at24 eeprom, didn't work as expected. Yes, we had the same this week/last week. > Apparently, there might be some timing issue, when I put printk() into the at24 > driver eeprom write function, it "fixed" itself. Though, replacing the i2c > driver with i2c gpio also fixed the issue, so I suspect the i2c driver has some > flaw in it. Try removing the printk and use the module paramter "io_limit=24" for at24. Does this help? (Or bs<=24 with dd) > If noone has any fixes already, I'll debug this tonight or so. The write FIFO overflows, since it only can carry 8 words. There is currently no check for that. One solution would be to check the FIFO status and fill them as needed. This will probably require additional locking, so I think the proper solution would be to use DMA for transfers bigger than the write FIFO size (we would get MX23 support then, too). Sadly, we don't have DMA support yet and I don't have time to implement it. I am thinking if such transfers which would fail anyway, should currently be rejected or if the driver should depend on BROKEN or both. I am still undecided, though. Please also check the patch I sent yesterday, there is also another one coming after I get confirmation from a customer. Regards, Wolfram -- Pengutronix e.K. | Wolfram Sang | Industrial Linux Solutions | http://www.pengutronix.de/ | -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 198 bytes Desc: Digital signature URL: <http://lists.infradead.org/pipermail/linux-arm-kernel/attachments/20120426/e69a67b6/attachment.sig>
next prev parent reply other threads:[~2012-04-26 11:42 UTC|newest] Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top 2012-04-26 11:26 possible MXS-i2c bug Marek Vasut 2012-04-26 11:41 ` Fabio Estevam [not found] ` <201204261326.29388.marex-ynQEQJNshbs@public.gmane.org> 2012-04-26 11:42 ` Wolfram Sang [this message] 2012-04-26 11:42 ` Wolfram Sang [not found] ` <20120426114201.GC3548-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org> 2012-04-26 23:10 ` Marek Vasut 2012-04-26 23:10 ` Marek Vasut [not found] ` <201204270110.21377.marex-ynQEQJNshbs@public.gmane.org> 2012-04-27 14:59 ` Wolfram Sang 2012-04-27 14:59 ` Wolfram Sang [not found] ` <20120427145936.GD16504-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org> 2012-04-27 15:08 ` Marek Vasut 2012-04-27 15:08 ` Marek Vasut [not found] ` <201204271708.53467.marex-ynQEQJNshbs@public.gmane.org> 2012-04-27 15:41 ` Wolfram Sang 2012-04-27 15:41 ` Wolfram Sang [not found] ` <20120427154119.GF16504-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org> 2012-04-27 15:53 ` Marek Vasut 2012-04-27 15:53 ` Marek Vasut [not found] ` <201204271753.39516.marex-ynQEQJNshbs@public.gmane.org> 2012-04-27 16:37 ` Wolfram Sang 2012-04-27 16:37 ` Wolfram Sang [not found] ` <20120427163756.GH16504-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org> 2012-04-28 3:03 ` [TEST PATCH] mxs-i2c DMA support Marek Vasut 2012-04-28 3:03 ` Marek Vasut
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