From: Nishanth Menon <nm@ti.com>
To: "Kattungal, Deepak" <deepak.k@ti.com>
Cc: linux-omap <linux-omap@vger.kernel.org>,
"Raja, Govindraj" <govindraj.raja@ti.com>,
Kevin Hilman <khilman@deeprootsystems.com>,
Tero Kristo <tero.kristo@nokia.com>
Subject: Re: [PM][PATCH 2/4] OMAP3: Serial: Errata i202: fix for MDR1 access
Date: Fri, 9 Apr 2010 12:21:02 -0500 [thread overview]
Message-ID: <4BBF61FE.3060807@ti.com> (raw)
In-Reply-To: <FCCFB4CDC6E5564B9182F639FC3560870304A6595E@dbde02.ent.ti.com>
Kattungal, Deepak had written, on 04/09/2010 12:06 PM, the following:
[..]
>> + /* TX and RX FIFO Clear; FIFO dis */
>> + serial_write_reg(p, UART_FCR, 0xA6);
> NAK
> Late realization: should be checking if FIFO clear actually occurred
> before proceeding (FIFO clear bits will be cleared by h/w once it is
> complete,
> so need to add a
> /* wait till TX and RX fifos are cleard by h/w */
> while(serial_read_reg(p, UART_FCR) & 0x06)
> ;
>
> Deepak : The FCR is a Write-Only Register, the read to it wont return the correct value. If at all we need to add a check,
>the LSR should be read for the status of the FIFO. The same follows
for the below section also.
Gee thx. Since RX fifo empty bit is 0 when empty and tx_fifo_empty bit
is 1 when empty, i will change to:
while( 0x20 != (serial_read_reg(p, UART_LSR) & 0x21))
;
Also From errata it does not require to make sure that shift register
also needs to be empty.. we could save a few nano seconds by not using that.
--
Regards,
Nishanth Menon
next prev parent reply other threads:[~2010-04-09 17:21 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-08 17:54 [PM][PATCH 0/4] OMAP3: Serial Misc fixes Nishanth Menon
2010-04-08 17:54 ` [PM][PATCH 1/4] OMAP3: Serial: Add context save and restore for mcr Nishanth Menon
2010-04-08 17:54 ` [PM][PATCH 2/4] OMAP3: Serial: Errata i202: fix for MDR1 access Nishanth Menon
2010-04-08 17:54 ` [PM][PATCH 3/4] OMAP3: Serial: remove initialization sparse warnings Nishanth Menon
2010-04-08 17:54 ` [PM][PATCH 4/4] OMAP3: Serial: kill dev_attr_sleep_timeout sparse warn Nishanth Menon
2010-05-05 23:57 ` Kevin Hilman
2010-04-09 17:00 ` [PM][PATCH 2/4] OMAP3: Serial: Errata i202: fix for MDR1 access Nishanth Menon
2010-04-09 17:06 ` Kattungal, Deepak
2010-04-09 17:21 ` Nishanth Menon [this message]
2010-05-05 23:49 ` [PM][PATCH 1/4] OMAP3: Serial: Add context save and restore for mcr Kevin Hilman
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