From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 29004E7D245 for ; Tue, 26 Sep 2023 07:37:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232621AbjIZHhy (ORCPT ); Tue, 26 Sep 2023 03:37:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51614 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229617AbjIZHhx (ORCPT ); Tue, 26 Sep 2023 03:37:53 -0400 Received: from muru.com (muru.com [72.249.23.125]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id DDDC8DC; Tue, 26 Sep 2023 00:37:46 -0700 (PDT) Received: from localhost (localhost [127.0.0.1]) by muru.com (Postfix) with ESMTPS id 2D61380A3; Tue, 26 Sep 2023 07:37:46 +0000 (UTC) Date: Tue, 26 Sep 2023 10:37:44 +0300 From: Tony Lindgren To: Sean Young Cc: Ivaylo Dimitrov , linux-media@vger.kernel.org, Russell King , Mauro Carvalho Chehab , Thierry Reding , Uwe =?utf-8?Q?Kleine-K=C3=B6nig?= , Timo Kokkonen , Pali =?utf-8?B?Um9ow6Fy?= , "Sicelo A . Mhlongo" , linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-pwm@vger.kernel.org Subject: Re: [PATCH v5 2/2] media: rc: remove ir-rx51 in favour of generic pwm-ir-tx Message-ID: <20230926073744.GA5285@atomide.com> References: <99f0042f-538c-bcaf-96fd-bac24a87f88e@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-omap@vger.kernel.org * Sean Young [230926 07:16]: > On Mon, Sep 25, 2023 at 07:06:44PM +0300, Ivaylo Dimitrov wrote: > > On 1.09.23 г. 17:18 ч., Sean Young wrote: > > > The ir-rx51 is a pwm-based TX driver specific to the N900. This can be > > > handled entirely by the generic pwm-ir-tx driver, and in fact the > > > pwm-ir-tx driver has been compatible with ir-rx51 from the start. > > > > > > > Unfortunately, pwm-ir-tx does not work on n900. My investigation shows that > > for some reason usleep_range() sleeps for at least 300-400 us more than what > > interval it is requested to sleep. I played with cyclictest from rt-tests > > package and it gives similar results - increasing the priority helps, but I > > was not able to make it sleep for less that 300 us in average. I tried > > cpu_latency_qos_add_request() in pwm-ir-tx, but it made no difference. > > > > I get similar results on motorola droid4 (OMAP4), albeit there average sleep > > is in 200-300 us range, which makes me believe that either OMAPs have issues > > with hrtimers or the config we use has some issue which leads to scheduler > > latency. Or, something else... > > The pwm-ir-tx driver does suffer from this problem, but I was under the > impression that the ir-rx51 has the same problem. > > > In either case help is appreciated to dig further trying to find the reason > > for such a big delay. > > pwm-ir-tx uses usleep_range() and ir-rx51 uses hrtimers. I thought that > usleep_range() uses hrtimers; however if you're not seeing the same delay > on ir-rx51 then maybe it's time to switch pwm-ir-tx to hrtimers. Maybe using fsleep() fixes this issue? See commit c6af13d33475 ("timer: add fsleep for flexible sleeping"), and Documentation/timers/timers-howto.rst. The long wake-up time for an idle state could explain the values. I think Ivaylo already tested with most cpuidle states disabled via sysfs though. > I don't have a n900 to test on, unfortunately. If you want one for development, the maemo folks cc:ed here likely have some available devices. Regards, Tony From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 1B25BE7D246 for ; Tue, 26 Sep 2023 07:38:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=sccNcm2Wzz12cAwNqWkl8snFXT3K6oEuF2EWNcnpAQo=; b=Z2+EPvqHDV/9jx SEp9ucqFssoqtC/tooIfVhd2uGoK02Mk/3OXtv6PFnjIxUM5uTp/mUlu2xI1Lwd1stJdWHsmXbZW5 WBfWii+EhyYtKdwCqSsuPYpYq85Ml3VoUIYFs7Cc+SZE6NXFjk3Qyt4wjQExbgG4LH1v1WqGm+0w0 Q4H0mAfusFEsy9ZJCpLEcrKZyPyTVxwH5L98fL+fY9AU8qe8RvZe2HsCzCHTsOn70798UNSiro7Dw 06GzfsOZIsyh0nZCya1q20RfunqYleI+gfVLgo82KL/ZjadwObL1k8DAkd/aweFLFXQMWqXluYxIb I7uipzIaEgAr4YXIY5Eg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1ql2di-00Fo8e-1O; Tue, 26 Sep 2023 07:37:50 +0000 Received: from muru.com ([72.249.23.125]) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1ql2df-00Fo84-0d for linux-arm-kernel@lists.infradead.org; Tue, 26 Sep 2023 07:37:48 +0000 Received: from localhost (localhost [127.0.0.1]) by muru.com (Postfix) with ESMTPS id 2D61380A3; Tue, 26 Sep 2023 07:37:46 +0000 (UTC) Date: Tue, 26 Sep 2023 10:37:44 +0300 From: Tony Lindgren To: Sean Young Cc: Ivaylo Dimitrov , linux-media@vger.kernel.org, Russell King , Mauro Carvalho Chehab , Thierry Reding , Uwe =?utf-8?Q?Kleine-K=C3=B6nig?= , Timo Kokkonen , Pali =?utf-8?B?Um9ow6Fy?= , "Sicelo A . Mhlongo" , linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-pwm@vger.kernel.org Subject: Re: [PATCH v5 2/2] media: rc: remove ir-rx51 in favour of generic pwm-ir-tx Message-ID: <20230926073744.GA5285@atomide.com> References: <99f0042f-538c-bcaf-96fd-bac24a87f88e@gmail.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230926_003747_277228_86C37BF7 X-CRM114-Status: GOOD ( 26.01 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org KiBTZWFuIFlvdW5nIDxzZWFuQG1lc3Mub3JnPiBbMjMwOTI2IDA3OjE2XToKPiBPbiBNb24sIFNl cCAyNSwgMjAyMyBhdCAwNzowNjo0NFBNICswMzAwLCBJdmF5bG8gRGltaXRyb3Ygd3JvdGU6Cj4g PiBPbiAxLjA5LjIzINCzLiAxNzoxOCDRhy4sIFNlYW4gWW91bmcgd3JvdGU6Cj4gPiA+IFRoZSBp ci1yeDUxIGlzIGEgcHdtLWJhc2VkIFRYIGRyaXZlciBzcGVjaWZpYyB0byB0aGUgTjkwMC4gVGhp cyBjYW4gYmUKPiA+ID4gaGFuZGxlZCBlbnRpcmVseSBieSB0aGUgZ2VuZXJpYyBwd20taXItdHgg ZHJpdmVyLCBhbmQgaW4gZmFjdCB0aGUKPiA+ID4gcHdtLWlyLXR4IGRyaXZlciBoYXMgYmVlbiBj b21wYXRpYmxlIHdpdGggaXItcng1MSBmcm9tIHRoZSBzdGFydC4KPiA+ID4gCj4gPiAKPiA+IFVu Zm9ydHVuYXRlbHksIHB3bS1pci10eCBkb2VzIG5vdCB3b3JrIG9uIG45MDAuIE15IGludmVzdGln YXRpb24gc2hvd3MgdGhhdAo+ID4gZm9yIHNvbWUgcmVhc29uIHVzbGVlcF9yYW5nZSgpIHNsZWVw cyBmb3IgYXQgbGVhc3QgMzAwLTQwMCB1cyBtb3JlIHRoYW4gd2hhdAo+ID4gaW50ZXJ2YWwgaXQg aXMgcmVxdWVzdGVkIHRvIHNsZWVwLiBJIHBsYXllZCB3aXRoIGN5Y2xpY3Rlc3QgZnJvbSBydC10 ZXN0cwo+ID4gcGFja2FnZSBhbmQgaXQgZ2l2ZXMgc2ltaWxhciByZXN1bHRzIC0gaW5jcmVhc2lu ZyB0aGUgcHJpb3JpdHkgaGVscHMsIGJ1dCBJCj4gPiB3YXMgbm90IGFibGUgdG8gbWFrZSBpdCBz bGVlcCBmb3IgbGVzcyB0aGF0IDMwMCB1cyBpbiBhdmVyYWdlLiBJIHRyaWVkCj4gPiBjcHVfbGF0 ZW5jeV9xb3NfYWRkX3JlcXVlc3QoKSBpbiBwd20taXItdHgsIGJ1dCBpdCBtYWRlIG5vIGRpZmZl cmVuY2UuCj4gPiAKPiA+IEkgZ2V0IHNpbWlsYXIgcmVzdWx0cyBvbiBtb3Rvcm9sYSBkcm9pZDQg KE9NQVA0KSwgYWxiZWl0IHRoZXJlIGF2ZXJhZ2Ugc2xlZXAKPiA+IGlzIGluIDIwMC0zMDAgdXMg cmFuZ2UsIHdoaWNoIG1ha2VzIG1lIGJlbGlldmUgdGhhdCBlaXRoZXIgT01BUHMgaGF2ZSBpc3N1 ZXMKPiA+IHdpdGggaHJ0aW1lcnMgb3IgdGhlIGNvbmZpZyB3ZSB1c2UgaGFzIHNvbWUgaXNzdWUg d2hpY2ggbGVhZHMgdG8gc2NoZWR1bGVyCj4gPiBsYXRlbmN5LiBPciwgc29tZXRoaW5nIGVsc2Uu Li4KPiAKPiBUaGUgcHdtLWlyLXR4IGRyaXZlciBkb2VzIHN1ZmZlciBmcm9tIHRoaXMgcHJvYmxl bSwgYnV0IEkgd2FzIHVuZGVyIHRoZQo+IGltcHJlc3Npb24gdGhhdCB0aGUgaXItcng1MSBoYXMg dGhlIHNhbWUgcHJvYmxlbS4KPiAKPiA+IEluIGVpdGhlciBjYXNlIGhlbHAgaXMgYXBwcmVjaWF0 ZWQgdG8gZGlnIGZ1cnRoZXIgdHJ5aW5nIHRvIGZpbmQgdGhlIHJlYXNvbgo+ID4gZm9yIHN1Y2gg YSBiaWcgZGVsYXkuCj4gCj4gcHdtLWlyLXR4IHVzZXMgdXNsZWVwX3JhbmdlKCkgYW5kIGlyLXJ4 NTEgdXNlcyBocnRpbWVycy4gSSB0aG91Z2h0IHRoYXQKPiB1c2xlZXBfcmFuZ2UoKSB1c2VzIGhy dGltZXJzOyBob3dldmVyIGlmIHlvdSdyZSBub3Qgc2VlaW5nIHRoZSBzYW1lIGRlbGF5Cj4gb24g aXItcng1MSB0aGVuIG1heWJlIGl0J3MgdGltZSB0byBzd2l0Y2ggcHdtLWlyLXR4IHRvIGhydGlt ZXJzLgoKTWF5YmUgdXNpbmcgZnNsZWVwKCkgZml4ZXMgdGhpcyBpc3N1ZT8gU2VlIGNvbW1pdCBj NmFmMTNkMzM0NzUgKCJ0aW1lcjogYWRkCmZzbGVlcCBmb3IgZmxleGlibGUgc2xlZXBpbmciKSwg YW5kIERvY3VtZW50YXRpb24vdGltZXJzL3RpbWVycy1ob3d0by5yc3QuCgpUaGUgbG9uZyB3YWtl LXVwIHRpbWUgZm9yIGFuIGlkbGUgc3RhdGUgY291bGQgZXhwbGFpbiB0aGUgdmFsdWVzLiBJIHRo aW5rCkl2YXlsbyBhbHJlYWR5IHRlc3RlZCB3aXRoIG1vc3QgY3B1aWRsZSBzdGF0ZXMgZGlzYWJs ZWQgdmlhIHN5c2ZzIHRob3VnaC4KCj4gSSBkb24ndCBoYXZlIGEgbjkwMCB0byB0ZXN0IG9uLCB1 bmZvcnR1bmF0ZWx5LgoKSWYgeW91IHdhbnQgb25lIGZvciBkZXZlbG9wbWVudCwgdGhlIG1hZW1v IGZvbGtzIGNjOmVkIGhlcmUgbGlrZWx5IGhhdmUKc29tZSBhdmFpbGFibGUgZGV2aWNlcy4KClJl Z2FyZHMsCgpUb255CgpfX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fXwpsaW51eC1hcm0ta2VybmVsIG1haWxpbmcgbGlzdApsaW51eC1hcm0ta2VybmVsQGxpc3Rz LmluZnJhZGVhZC5vcmcKaHR0cDovL2xpc3RzLmluZnJhZGVhZC5vcmcvbWFpbG1hbi9saXN0aW5m by9saW51eC1hcm0ta2VybmVsCg==