Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Feedback-ID: i56a14606:Fastmail
User-Agent: Cyrus-JMAP/3.7.0-alpha0-1185-g841157300a-fm-20221208.002-g84115730
Mime-Version: 1.0
Message-Id: <179739a0-5d75-412b-964b-16d5cb6d306d@app.fastmail.com>
In-Reply-To: <20230112140524.GK730856@darkstar.musicnaut.iki.fi>
References: <20230112083746.9551-1-lukas.bulwahn@gmail.com>
 <20230112083746.9551-4-lukas.bulwahn@gmail.com>
 <3f2663ff-ff3f-4632-853a-ba4d38df9701@app.fastmail.com>
 <Y7/YiMPIDN0Cf5Ky@atomide.com>
 <c9821df0-cd3e-43a0-b903-430d1251d51c@app.fastmail.com>
 <20230112140524.GK730856@darkstar.musicnaut.iki.fi>
Date:   Thu, 12 Jan 2023 15:31:20 +0100
From:   "Arnd Bergmann" <arnd@arndb.de>
To:     "Aaro Koskinen" <aaro.koskinen@iki.fi>
Cc:     "Tony Lindgren" <tony@atomide.com>,
        "Lukas Bulwahn" <lukas.bulwahn@gmail.com>,
        "Janusz Krzysztofik" <jmkrzyszt@gmail.com>,
        "Krzysztof Kozlowski" <krzysztof.kozlowski@linaro.org>,
        linux-arm-kernel@lists.infradead.org,
        Linux-OMAP <linux-omap@vger.kernel.org>,
        linux-usb@vger.kernel.org, linux-samsung-soc@vger.kernel.org,
        kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/4] usb: remove OMAP USB Device Controller and OHCI support for
 OMAP1/2 chips
Content-Type: text/plain
Precedence: bulk

On Thu, Jan 12, 2023, at 15:05, Aaro Koskinen wrote:
> On Thu, Jan 12, 2023 at 11:19:53AM +0100, Arnd Bergmann wrote:
>> On Thu, Jan 12, 2023, at 10:53, Tony Lindgren wrote:
>> 
>> So if we want to kill off the old DMA stuff there is actually
>> a choice between either making omap_udc PIO-only or converting
>> it to use the standard dmaengine interface.
>
> I use this driver on Palm TE and 770, and without it those boards would
> be useless for my use cases. Also DMA doubles the throughput, probably
> also power usage is smaller.

Ok, if the performance is important, converting to dmaengine
is probably best. Do you know if this is just a straightforward
replacement of the function calls, or are there technical reasons
why it's not using the dmaengine interface yet?

     Arnd