From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753685AbeD2PWu (ORCPT ); Sun, 29 Apr 2018 11:22:50 -0400 Received: from sender-of-o52.zoho.com ([135.84.80.217]:21495 "EHLO sender-of-o52.zoho.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753318AbeD2PWt (ORCPT ); Sun, 29 Apr 2018 11:22:49 -0400 Date: Sun, 29 Apr 2018 11:22:25 -0400 From: Marcin Ziemianowicz To: Boris Brezillon Cc: Boris Brezillon , Nicolas Ferre , Alexandre Belloni , Michael Turquette , Stephen Boyd , linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3] clk: at91: PLL recalc_rate() now using cached MUL+DIV values Message-ID: <20180429152225.GA742@hak8or> References: <20180427175609.GA83298@hak8or> <20180429151710.4ca68978@bbrezillon> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180429151710.4ca68978@bbrezillon> User-Agent: Mutt/1.9.5 (2018-04-13) X-ZohoMailClient: External Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Apr 29, 2018 at 03:17:10PM +0200, Boris Brezillon wrote: > Hi Marcin, > > On Fri, 27 Apr 2018 13:56:09 -0400 > Marcin Ziemianowicz wrote: > > > Stephen Boyd , > > linux-clk@vger.kernel.org, > > linux-arm-kernel@lists.infradead.org, > > linux-kernel@vger.kernel.org > > Bcc: > > Subject: [PATCH v3] clk: at91: PLL recalc_rate() now using cached MUL and DIV > > values > > Reply-To: > > Hm, I don't know how you prepared and sent your patch, but you shouldn't > have these fields in the body of your email. Please use git format-patch > to prepare the patch and then git send-email to send it. I have been using Mutt this entire time with the idea of being able to use Mutt for both sending the patch and replying to emails, but I am still fumbling around with this (as you can see). I used git format-patch HEAD^ and I think I additionally bungled something when using Mutt. I will try git send-email instead since it seems less error prone on my end. > > > > > When a USB device is connected to the USB host port on the SAM9N12 then > > you get "-62" error which seems to indicate USB replies from the device > > are timing out. Based on a logic sniffer, I saw the USB bus was running > > at half speed. > > > > The PLL code uses cached MUL and DIV values which get set in set_rate() > > and applied in prepare(), but the recalc_rate() function instead > > queries the hardware instead of using these cached values. Therefore, > > if recalc_rate() is called between a set_rate() and prepare(), the > > wrong frequency is calculated and later the USB clock divider for the > > SAM9N12 SOC will be configured for an incorrect clock. > > > > In my case, the PLL hardware was set to 96 Mhz before the OHCI > > driver loads, and therefore the usb clock divider was being set > > to /2 even though the OHCI driver set the PLL to 48 Mhz. > > > > As an alternative explanation, I noticed this was fixed in the past: > > http://lists.infradead.org/pipermail/linux-arm-kernel/2014-September/283502.html > > but was later changed back via a large patch (maybe by mistake?): > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=1bdf02326b71eae7e9b4b335b881856aaf9d1af6 > > Yep, probably by mistake. I started this rework long before it has been > submitted to the ML, so I probably messed something up when rebasing. > Ah, it happens I guess. 99 little bugs in the code, 99 litle bugs. Take one down, patch it around, 117 little bugs in the code. ;) > Also, prefer commit IDs to links to the ML archive. The above would > sentence would give: > > " > As an alternative explanation, I noticed this was fixed in the past by > 87e2ed338f1b ("clk: at91: fix recalc_rate implementation of PLL > driver") but the bug was later re-introduced by 1bdf02326b71 ("clk: > at91: make use of syscon/regmap internally"). > " > Ah, I was wondering what the best way is to reference old commits. Thank you, will do! > > The following comment and the changelog should be placed after the > '---' line, so that it's not part of the commit message. > > > Thank you for bearing with me about this Boris. > > > > Changes since V2: > > Removed all logging/debug messages I added > > > Comment by Boris Brezillon about my fix being wrong addressed > > Changes since V1: > > Added patch set cover letter > > Shortened lines which were over >80 characters long > > > Comment by Greg Kroah-Hartman about "from" field in email addressed > > > Comment by Alan Stern about redundant debug lines addressed > > > > You should add Fixes and Cc-stable tags so that the fix is backported > to stable branches: > > Fixes: 1bdf02326b71 ("clk: at91: make use of syscon/regmap internally) > Cc: > > > Signed-off-by: Marcin Ziemianowicz > > --- > > drivers/clk/at91/clk-pll.c | 13 +------------ > > 1 file changed, 1 insertion(+), 12 deletions(-) > > > > diff --git a/drivers/clk/at91/clk-pll.c b/drivers/clk/at91/clk-pll.c > > index 7d3223fc..cc6e0364 100644 > > --- a/drivers/clk/at91/clk-pll.c > > +++ b/drivers/clk/at91/clk-pll.c > > @@ -132,19 +132,8 @@ static unsigned long clk_pll_recalc_rate(struct clk_hw *hw, > > unsigned long parent_rate) > > { > > struct clk_pll *pll = to_clk_pll(hw); > > - unsigned int pllr; > > - u16 mul; > > - u8 div; > > - > > - regmap_read(pll->regmap, PLL_REG(pll->id), &pllr); > > - > > - div = PLL_DIV(pllr); > > - mul = PLL_MUL(pllr, pll->layout); > > - > > - if (!div || !mul) > > - return 0; > > > > - return (parent_rate / div) * (mul + 1); > > + return return (parent_rate / pll->div) * (pll->mul + 1); > > The fix looks good. Let me know if you struggle with git > format-patch/send-email and I'll try to help you (or send the patch for > you if you don't care learning the process, but I think it's better if > you learn how to submit patches). > I definitely do want to learn how to do this myself, but thank you for the offer! I just hope I am not taking up too much of your and others time with me bumbling around like this. > Thanks, > > Boris > > > } > > > > static long clk_pll_get_best_div_mul(struct clk_pll *pll, unsigned long rate, > From mboxrd@z Thu Jan 1 00:00:00 1970 From: marcin@ziemianowicz.com (Marcin Ziemianowicz) Date: Sun, 29 Apr 2018 11:22:25 -0400 Subject: [PATCH v3] clk: at91: PLL recalc_rate() now using cached MUL+DIV values In-Reply-To: <20180429151710.4ca68978@bbrezillon> References: <20180427175609.GA83298@hak8or> <20180429151710.4ca68978@bbrezillon> Message-ID: <20180429152225.GA742@hak8or> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Sun, Apr 29, 2018 at 03:17:10PM +0200, Boris Brezillon wrote: > Hi Marcin, > > On Fri, 27 Apr 2018 13:56:09 -0400 > Marcin Ziemianowicz wrote: > > > Stephen Boyd , > > linux-clk at vger.kernel.org, > > linux-arm-kernel at lists.infradead.org, > > linux-kernel at vger.kernel.org > > Bcc: > > Subject: [PATCH v3] clk: at91: PLL recalc_rate() now using cached MUL and DIV > > values > > Reply-To: > > Hm, I don't know how you prepared and sent your patch, but you shouldn't > have these fields in the body of your email. Please use git format-patch > to prepare the patch and then git send-email to send it. I have been using Mutt this entire time with the idea of being able to use Mutt for both sending the patch and replying to emails, but I am still fumbling around with this (as you can see). I used git format-patch HEAD^ and I think I additionally bungled something when using Mutt. I will try git send-email instead since it seems less error prone on my end. > > > > > When a USB device is connected to the USB host port on the SAM9N12 then > > you get "-62" error which seems to indicate USB replies from the device > > are timing out. Based on a logic sniffer, I saw the USB bus was running > > at half speed. > > > > The PLL code uses cached MUL and DIV values which get set in set_rate() > > and applied in prepare(), but the recalc_rate() function instead > > queries the hardware instead of using these cached values. Therefore, > > if recalc_rate() is called between a set_rate() and prepare(), the > > wrong frequency is calculated and later the USB clock divider for the > > SAM9N12 SOC will be configured for an incorrect clock. > > > > In my case, the PLL hardware was set to 96 Mhz before the OHCI > > driver loads, and therefore the usb clock divider was being set > > to /2 even though the OHCI driver set the PLL to 48 Mhz. > > > > As an alternative explanation, I noticed this was fixed in the past: > > http://lists.infradead.org/pipermail/linux-arm-kernel/2014-September/283502.html > > but was later changed back via a large patch (maybe by mistake?): > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=1bdf02326b71eae7e9b4b335b881856aaf9d1af6 > > Yep, probably by mistake. I started this rework long before it has been > submitted to the ML, so I probably messed something up when rebasing. > Ah, it happens I guess. 99 little bugs in the code, 99 litle bugs. Take one down, patch it around, 117 little bugs in the code. ;) > Also, prefer commit IDs to links to the ML archive. The above would > sentence would give: > > " > As an alternative explanation, I noticed this was fixed in the past by > 87e2ed338f1b ("clk: at91: fix recalc_rate implementation of PLL > driver") but the bug was later re-introduced by 1bdf02326b71 ("clk: > at91: make use of syscon/regmap internally"). > " > Ah, I was wondering what the best way is to reference old commits. Thank you, will do! > > The following comment and the changelog should be placed after the > '---' line, so that it's not part of the commit message. > > > Thank you for bearing with me about this Boris. > > > > Changes since V2: > > Removed all logging/debug messages I added > > > Comment by Boris Brezillon about my fix being wrong addressed > > Changes since V1: > > Added patch set cover letter > > Shortened lines which were over >80 characters long > > > Comment by Greg Kroah-Hartman about "from" field in email addressed > > > Comment by Alan Stern about redundant debug lines addressed > > > > You should add Fixes and Cc-stable tags so that the fix is backported > to stable branches: > > Fixes: 1bdf02326b71 ("clk: at91: make use of syscon/regmap internally) > Cc: > > > Signed-off-by: Marcin Ziemianowicz > > --- > > drivers/clk/at91/clk-pll.c | 13 +------------ > > 1 file changed, 1 insertion(+), 12 deletions(-) > > > > diff --git a/drivers/clk/at91/clk-pll.c b/drivers/clk/at91/clk-pll.c > > index 7d3223fc..cc6e0364 100644 > > --- a/drivers/clk/at91/clk-pll.c > > +++ b/drivers/clk/at91/clk-pll.c > > @@ -132,19 +132,8 @@ static unsigned long clk_pll_recalc_rate(struct clk_hw *hw, > > unsigned long parent_rate) > > { > > struct clk_pll *pll = to_clk_pll(hw); > > - unsigned int pllr; > > - u16 mul; > > - u8 div; > > - > > - regmap_read(pll->regmap, PLL_REG(pll->id), &pllr); > > - > > - div = PLL_DIV(pllr); > > - mul = PLL_MUL(pllr, pll->layout); > > - > > - if (!div || !mul) > > - return 0; > > > > - return (parent_rate / div) * (mul + 1); > > + return return (parent_rate / pll->div) * (pll->mul + 1); > > The fix looks good. Let me know if you struggle with git > format-patch/send-email and I'll try to help you (or send the patch for > you if you don't care learning the process, but I think it's better if > you learn how to submit patches). > I definitely do want to learn how to do this myself, but thank you for the offer! I just hope I am not taking up too much of your and others time with me bumbling around like this. > Thanks, > > Boris > > > } > > > > static long clk_pll_get_best_div_mul(struct clk_pll *pll, unsigned long rate, >