From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934088AbcIWIHk (ORCPT ); Fri, 23 Sep 2016 04:07:40 -0400 Received: from lucky1.263xmail.com ([211.157.147.131]:42808 "EHLO lucky1.263xmail.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933526AbcIWIH3 (ORCPT ); Fri, 23 Sep 2016 04:07:29 -0400 X-263anti-spam: KSV:0; X-MAIL-GRAY: 1 X-MAIL-DELIVERY: 0 X-KSVirus-check: 0 X-ABS-CHECKED: 4 X-ADDR-CHECKED4: 1 X-RL-SENDER: shawn.lin@rock-chips.com X-FST-TO: xzy.xu@rock-chips.com X-SENDER-IP: 58.22.7.114 X-LOGIN-NAME: shawn.lin@rock-chips.com X-UNIQUE-TAG: X-ATTACHMENT-NUM: 0 X-DNS-TYPE: 0 Subject: Re: [RESEDN PATCH v2 3/4] mmc: sdhci: Don't try to switch to unsupported voltage To: Adrian Hunter References: <1474589577-11193-1-git-send-email-shawn.lin@rock-chips.com> <1474589577-11193-3-git-send-email-shawn.lin@rock-chips.com> <785df157-dadc-4dd3-76e9-aea3a0f031a5@intel.com> Cc: shawn.lin@rock-chips.com, Ulf Hansson , Jaehoon Chung , linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-rockchip@lists.infradead.org, Ziyuan Xu From: Shawn Lin Message-ID: <1df2cfcf-0c62-6539-24a0-941475f236d1@rock-chips.com> Date: Fri, 23 Sep 2016 16:07:11 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.3.0 MIME-Version: 1.0 In-Reply-To: <785df157-dadc-4dd3-76e9-aea3a0f031a5@intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 在 2016/9/23 15:12, Adrian Hunter 写道: > On 23/09/16 03:12, Shawn Lin wrote: >> From: Ziyuan Xu >> >> Sdhci shouldn't switch to the unsupported voltage if claiming >> that it can not support the requested voltage. Let's fix it. >> >> Signed-off-by: Ziyuan Xu >> Signed-off-by: Shawn Lin >> --- >> >> Changes in v2: None >> >> drivers/mmc/host/sdhci.c | 6 ++++-- >> 1 file changed, 4 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c >> index 4805566..b1f1edd 100644 >> --- a/drivers/mmc/host/sdhci.c >> +++ b/drivers/mmc/host/sdhci.c >> @@ -1845,7 +1845,8 @@ static int sdhci_start_signal_voltage_switch(struct mmc_host *mmc, >> >> switch (ios->signal_voltage) { >> case MMC_SIGNAL_VOLTAGE_330: >> - if (!(host->flags & SDHCI_SIGNALING_330)) >> + if (!(host->flags & SDHCI_SIGNALING_330) || >> + !(host->caps & SDHCI_CAN_VDD_330)) > > You are mixing signal voltage and supply voltage here. Note, I don't Oh, I see what you mean, driver could still set 3.3 voltage supply even they don't support 3V3 signal voltage. > believe all drivers set the capabilities correctly when they are using > regulators, but in any case this is not the place in the code to make such > assumptions. Indeed, there is a risk of breaking some drivers if they don't set the capabilities correctly. So, I think we could drop this patch since patch 4 is actually what we need in order to slove our problem. :) > > Better for the driver to remove SDHCI_SIGNALING_330 from flags when it is > not supported. > >> return -EINVAL; >> /* Set 1.8V Signal Enable in the Host Control2 register to 0 */ >> ctrl &= ~SDHCI_CTRL_VDD_180; >> @@ -1872,7 +1873,8 @@ static int sdhci_start_signal_voltage_switch(struct mmc_host *mmc, >> >> return -EAGAIN; >> case MMC_SIGNAL_VOLTAGE_180: >> - if (!(host->flags & SDHCI_SIGNALING_180)) >> + if (!(host->flags & SDHCI_SIGNALING_180) || >> + !(host->caps & SDHCI_CAN_VDD_180)) > > You are mixing signal voltage and supply voltage here, and this is not > correct: not being able to do 1.8V supply does not mean you can't do 1.8V > signaling. The SDHCI way of determining supported signal voltages is based > on supported transfer modes. > > If the driver can't get the transfer modes correct (e.g. we still don't have > MMC_CAP2_3_3V_ONLY_DDR or equivalent), remove SDHCI_SIGNALING_180 from the > flags. > >> return -EINVAL; >> if (!IS_ERR(mmc->supply.vqmmc)) { >> ret = mmc_regulator_set_vqmmc(mmc, ios); >> > > > > -- Best Regards Shawn Lin