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Re: [PATCH 6/12] drivers: PMC MSP71xx serial driver

To: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Subject: Re: [PATCH 6/12] drivers: PMC MSP71xx serial driver
From: Marc St-Jean <Marc_St-Jean@pmc-sierra.com>
Date: Tue, 27 Mar 2007 10:35:39 -0800
Cc: linux-mips@linux-mips.org
Original-recipient: rfc822;linux-mips@linux-mips.org
Sender: linux-mips-bounce@linux-mips.org
User-agent: Thunderbird 1.5.0.10 (X11/20070221)
Sergei Shtylyov wrote:
> Hello.
> 
> Marc St-Jean wrote:
> 
>  > Patch to add serial driver support for the PMC-Sierra
>  > MSP71xx devices.
> 
>  > Reposting patches as a single set at the request of akpm.
>  > Only 9 of 12 will be posted at this time, 3 more to follow
>  > when cleanups are complete.
> 
>  > Thanks,
>  > Marc
> 
>  > Signed-off-by: Marc St-Jean <Marc_St-Jean@pmc-sierra.com>
>  > ---
>  > Re-posting patch with recommended changes:
>  > -Implemented support for putchar() in msp_serial.c
> 
>  > diff --git a/arch/mips/pmc-sierra/msp71xx/msp_serial.c 
> b/arch/mips/pmc-sierra/msp71xx/msp_serial.c
>  > new file mode 100644
>  > index 0000000..3b956e9
>  > --- /dev/null
>  > +++ b/arch/mips/pmc-sierra/msp71xx/msp_serial.c
>  > @@ -0,0 +1,185 @@
> [...]
>  > +#ifdef CONFIG_KGDB
>  > +/*
>  > + * kgdb uses serial port 1 so the console can remain on port 0.
>  > + * To use port 0 change the definition to read as follows:
>  > + * #define DEBUG_PORT_BASE KSEG1ADDR(MSP_UART0_BASE)
>  > + */
>  > +#define DEBUG_PORT_BASE KSEG1ADDR(MSP_UART1_BASE)
>  > +
>  > +int putDebugChar(char c)
>  > +{
>  > +     volatile uint32_t *uart = (volatile uint32_t *)DEBUG_PORT_BASE;
>  > +     uint32_t val = (uint32_t)c;
>  > +
>  > +     local_irq_disable();
>  > +     while (!(uart[5] & 0x20)); /* Wait for TXRDY */
>  > +     uart[0] = val;
>  > +     while (!(uart[5] & 0x20)); /* Wait for TXRDY */
>  > +     local_irq_enable();
> 
>     Gah, why you decided to put local_irq_enable() there?!  KGDB expects
> interrupts to be *disabled* while it has control, else some subtle state
> corruptions will ensue, and it will eventually lock up. Please remove 
> these 2 calls completely.

Hmmm, this has been working for several months. I'll remove, retest and
resubmit.

Are you aware if this is the case for the "putchar" used by early_printk
as well?

Thanks,
Marc


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