From: Alan <alan@lxorguk.ukuu.org.uk>
To: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
ralf@linux-mips.org
Subject: Re: [PATCH 2.6.21-rc1] serial: serial_txx9 driver update
Date: Wed, 21 Feb 2007 16:48:26 +0000 [thread overview]
Message-ID: <20070221164826.61d0b5ea@lxorguk.ukuu.org.uk> (raw)
In-Reply-To: <20070222.003142.106263613.anemo@mba.ocn.ne.jp>
> +static void serial_txx9_initialize(struct uart_port *port)
> +{
> + struct uart_txx9_port *up = (struct uart_txx9_port *)port;
> +
> + sio_out(up, TXX9_SIFCR, TXX9_SIFCR_SWRST);
> +#ifdef CONFIG_CPU_TX49XX
> + /* TX4925 BUG WORKAROUND. Accessing SIOC register
> + * immediately after soft reset causes bus error. */
> + iob();
> + udelay(1);
> +#endif
Given this costs 1uS in a path that is not performance critical is it
worth putting the #ifdef/#endif in instead of having one set of code that
works for all ?
> + while (sio_in(up, TXX9_SIFCR) & TXX9_SIFCR_SWRST)
> + ;
Suppose it doesn't clear ? Should also use cpu_relax() in busy loops
so any processor variant with power management can do the right thing.
Neither of course are bugs you have added, just things you have moved that
seem worth asking about.
Acked-by: Alan Cox <alan@redhat.com>
next prev parent reply other threads:[~2007-02-21 15:46 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-02-21 15:31 Atsushi Nemoto
2007-02-21 16:48 ` Alan [this message]
2007-02-21 17:00 ` Ralf Baechle
2007-02-21 17:02 ` Atsushi Nemoto
2007-02-21 18:11 ` Alan
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