Message-ID: <44DA07D6.9010101@ru.mvista.com>
Date: Wed, 09 Aug 2006 20:05:42 +0400
From: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Organization: MontaVista Software Inc.
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To: Mikael Pettersson <mikpe@csd.uu.se>
Cc: albertl@mail.com, Mikael Pettersson <mikpe@it.uu.se>,
       linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org,
       alan@redhat.com, Unicorn Chang <uchang@tw.ibm.com>,
       Doug Maxey <dwm@enoyolf.org>
Subject: Re: libata pata_pdc2027x success on sparc64
References: <200607172358.k6HNwYhF002052@harpo.it.uu.se>	<44BD2370.8090506@ru.mvista.com>	<44C841B5.40806@tw.ibm.com> <17626.1619.653854.241578@alkaid.it.uu.se>
In-Reply-To: <17626.1619.653854.241578@alkaid.it.uu.se>
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Hello.

Mikael Pettersson wrote:

>  > The libata version has three improvements compared to the IDE version.
>  > 
>  > 1. The PLL calibration patches in the above URLs (for IDE)
>  > still need more improvement as done in the pdc_read_counter()
>  > of the libata version.
>  > 
>  > 2. The Promise 2027x adapters check the "set features - xfer mode"
>  >    and set the timing register automatically. However, the automatically
>  >    set values are not correct under 133MHz. Libata has a hook
>  >    pdc2027x_post_set_mode() to set the values back by software.
>  > 
>  > 3. ATAPI DMA is supported (please see pdc2027x_check_atapi_dma()).
>  >    Maybe we also need to add this to the IDE version.

> Do you know how large the difference is between the 20267 (old driver)
> and the 20269 (new driver) in the areas touched by these patches?

    Immense. They belong to the different families, register compatibe only in 
the standard PCI/BM IDE regisrer set -- hence was the driver split.

> Long ago I tried a 20267 PCI card in my PowerMac, and it had the same
> issues that the 20269 card had. So I'm interested in porting the
> calibration/timing fixes to pdc202xx_old.c.

    They don't apply to this driver at all.  The "older" chip family didn't 
have the PLL to calibrate.  It must be some different issue.

> /Mikael

WBR, Sergei
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