From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755777Ab3HZEeb (ORCPT ); Mon, 26 Aug 2013 00:34:31 -0400 Received: from mailout1.samsung.com ([203.254.224.24]:50814 "EHLO mailout1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755240Ab3HZEe3 (ORCPT ); Mon, 26 Aug 2013 00:34:29 -0400 X-AuditID: cbfee68e-b7f756d000004512-5a-521adad34389 From: Seungwon Jeon To: "'Doug Anderson'" , "'Chris Ball'" Cc: "'Jaehoon Chung'" , "'James Hogan'" , "'Grant Grundler'" , "'Alim Akhtar'" , "'Abhilash Kesavan'" , "'Tomasz Figa'" , "'Olof Johansson'" , linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org References: <1377188348-3418-1-git-send-email-dianders@chromium.org> <1377188348-3418-3-git-send-email-dianders@chromium.org> In-reply-to: <1377188348-3418-3-git-send-email-dianders@chromium.org> Subject: RE: [PATCH v6 2/3] mmc: dw_mmc: Honor requests to set the clock to 0 (turn off clock) Date: Mon, 26 Aug 2013 13:34:26 +0900 Message-id: <001201cea215$8c125e30$a4371a90$%jun@samsung.com> MIME-version: 1.0 Content-type: text/plain; charset=ks_c_5601-1987 Content-transfer-encoding: 7bit X-Mailer: Microsoft Office Outlook 12.0 Thread-index: Ac6fVCD/tR0GDp5+QKuVzjRJKPMdEgCv37jw Content-language: ko X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFvrHIsWRmVeSWpSXmKPExsVy+t8zQ93Lt6SCDDruclk8XrOYyeLBvG1s Fttfb2SzOLvsIJvFqyM/mCzezXvBbHHjVxurxeVdc9gsjvzvZ7Q4df0zm8WqXX8YHbg9Zjdc ZPHYOesuu0fPzjOMHoeurGX0uHKiidWjb8sqRo/Pm+QC2KO4bFJSczLLUov07RK4Mk7tm8tS cFOq4uY3iwbGXtEuRk4OCQETieMTP7NA2GISF+6tZ+ti5OIQEljGKLF/7UcmmKIzs/cxQyQW MUpc6pjDCJIQEvjDKDH1dRGIzSagJfH3zRtmEFtEwEvixe4HYA3MAo+YJO4umQ3kcAA11Euc e+ANUsMp4CrRfawHrF5YIEGiaflOsJksAqoS3dt6wGxeAVuJj42NLBC2oMSPyffAbGYBA4n3 s/pYIWx5ic1r3oKNlxBQl3j0VxfiBCOJSxfuMEGUiEjse/GOEeQcCYGpHBIfPhxihdglIPFt 8iEWiF5ZiU0HmCH+lZQ4uOIGywRGiVlINs9CsnkWks2zkKxYwMiyilE0tSC5oDgpvchIrzgx t7g0L10vOT93EyMk7vt2MN48YH2IMRlo/URmKdHkfGDayCuJNzQ2M7IwNTE1NjK3NCNNWEmc V63FOlBIID2xJDU7NbUgtSi+qDQntfgQIxMHp1QD45yHe7elnWZ/5+v+5p2IQezlHStFrRdz 331W+M0/jjPz3tZZqo2iv9/ob4nl0hRLm9jbe/eI8plss7X8Wu6rVnxcvkt6iVDOLzXnWnHZ 4NOti6Zuldpg9epNiI++kuG3lc/C3L+vtL77bbHCat+v6c+U5jYm/XvyOj/0xGy5yoYzEm2B b9kXTVBiKc5INNRiLipOBAByK8cAEQMAAA== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFrrNKsWRmVeSWpSXmKPExsVy+t9jAd3Lt6SCDP7PYbV4vGYxk8WDedvY LLa/3shmcXbZQTaLV0d+MFm8m/eC2eLGrzZWi8u75rBZHPnfz2hx6vpnNotVu/4wOnB7zG64 yOKxc9Zddo+enWcYPQ5dWcvoceVEE6tH35ZVjB6fN8kFsEc1MNpkpCampBYppOYl56dk5qXb KnkHxzvHm5oZGOoaWlqYKynkJeam2iq5+AToumXmAF2ppFCWmFMKFApILC5W0rfDNCE0xE3X AqYxQtc3JAiux8gADSSsY8w4tW8uS8FNqYqb3ywaGHtFuxg5OSQETCTOzN7HDGGLSVy4t56t i5GLQ0hgEaPEpY45jCAJIYE/jBJTXxeB2GwCWhJ/37wBaxAR8JJ4sfsBM0gDs8AjJom7S2YD ORxADfUS5x54g9RwCrhKdB/rAasXFkiQaFq+E2wmi4CqRPe2HjCbV8BW4mNjIwuELSjxY/I9 MJtZwEDi/aw+VghbXmLzmrdg4yUE1CUe/dWFOMFI4tKFO0wQJSIS+168Y5zAKDQLyaRZSCbN QjJpFpKWBYwsqxhFUwuSC4qT0nMN9YoTc4tL89L1kvNzNzGCk8ozqR2MKxssDjEKcDAq8fAG FkgFCbEmlhVX5h5ilOBgVhLhdXWQDBLiTUmsrEotyo8vKs1JLT7EmAz06ERmKdHkfGDCyyuJ NzQ2MTOyNDKzMDIxNydNWEmc90CrdaCQQHpiSWp2ampBahHMFiYOTqkGxvrW5zHzMv37kq+l RGzc9eCC5GlluciczULfnjcnci/iLUrv4Wr79MFp6gPmh7wzHJ8p8WfWamytT53soZJ6/2eh w48Fey7ICQU/udXOpVq+yF9jM0eY07aNJ3Z8k+zJWZo6SSmApT2W8ZSi6xHhcz8e3kr5kXbD v56pTWnuvMVJb5565Fx4qsRSnJFoqMVcVJwIABbGIH5uAwAA DLP-Filter: Pass X-MTR: 20000000000000000@CPGS X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, August 23, 2013, Doug Anderson wrote: > Previously the dw_mmc driver would ignore any requests to disable the > card's clock. This doesn't seem like a good thing in general, but had > one extra bad side effect in the following situtation: > * mmc core would set clk to 400kHz at boot time while initting > * mmc core would set clk to 0 since no card, but it would be ignored. > * suspend to ram and resume; clocks in the dw_mmc IP block are now 0 > but dw_mmc thinks that they're 400kHz (it ignored the set to 0). > * insert card > * mmc core would set clk to 400kHz which would be considered a no-op. > > Note that if there is no card in the slot and we do a suspend/resume > cycle, we _do_ still end up with differences in a dw_mmc register > dump, but the differences are clock related and we've got the clock > disabled both before and after, so this should be OK. > > Signed-off-by: Doug Anderson > --- > Changes in v6: > - Replaces previous pathes that ensured saving/restoring clocks. > > drivers/mmc/host/dw_mmc.c | 21 +++++++++++---------- > 1 file changed, 11 insertions(+), 10 deletions(-) > > diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c > index ee5f167..f6c7545 100644 > --- a/drivers/mmc/host/dw_mmc.c > +++ b/drivers/mmc/host/dw_mmc.c > @@ -635,7 +635,11 @@ static void dw_mci_setup_bus(struct dw_mci_slot *slot, bool force_clkinit) > u32 div; > u32 clk_en_a; > > - if (slot->clock != host->current_speed || force_clkinit) { > + if (slot->clock == 0) { > + mci_writel(host, CLKENA, 0); > + mci_send_cmd(slot, > + SDMMC_CMD_UPD_CLK | SDMMC_CMD_PRV_DAT_WAIT, 0); Basically dw_mmc driver uses host's low power mode(auto clock gating) So, how about keeping origin code rather than programming clock setting to '0'? > + } else if (slot->clock != host->current_speed || force_clkinit) { And then, if condition('slot->clock is not zero') is added in order to allow to set clock, print messages which Jaehoon pointed would be solved. Thanks, Seungwon Jeon > div = host->bus_hz / slot->clock; > if (host->bus_hz % slot->clock && host->bus_hz > slot->clock) > /* > @@ -675,9 +679,8 @@ static void dw_mci_setup_bus(struct dw_mci_slot *slot, bool force_clkinit) > /* inform CIU */ > mci_send_cmd(slot, > SDMMC_CMD_UPD_CLK | SDMMC_CMD_PRV_DAT_WAIT, 0); > - > - host->current_speed = slot->clock; > } > + host->current_speed = slot->clock; > > /* Set the current slot bus width */ > mci_writel(host, CTYPE, (slot->ctype << slot->id)); > @@ -807,13 +810,11 @@ static void dw_mci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios) > > mci_writel(slot->host, UHS_REG, regs); > > - if (ios->clock) { > - /* > - * Use mirror of ios->clock to prevent race with mmc > - * core ios update when finding the minimum. > - */ > - slot->clock = ios->clock; > - } > + /* > + * Use mirror of ios->clock to prevent race with mmc > + * core ios update when finding the minimum. > + */ > + slot->clock = ios->clock; > > if (drv_data && drv_data->set_ios) > drv_data->set_ios(slot->host, ios); > -- > 1.8.3 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-mmc" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html