From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751905AbcAVDHj (ORCPT ); Thu, 21 Jan 2016 22:07:39 -0500 Received: from lucky1.263xmail.com ([211.157.147.131]:46271 "EHLO lucky1.263xmail.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751648AbcAVDHb (ORCPT ); Thu, 21 Jan 2016 22:07:31 -0500 X-263anti-spam: KSV:0; X-MAIL-GRAY: 1 X-MAIL-DELIVERY: 0 X-KSVirus-check: 0 X-ABS-CHECKED: 4 X-ADDR-CHECKED: 0 X-RL-SENDER: shawn.lin@rock-chips.com X-FST-TO: linux-kernel@vger.kernel.org X-SENDER-IP: 58.22.7.114 X-LOGIN-NAME: shawn.lin@rock-chips.com X-UNIQUE-TAG: <667a6f9a13278f680879664f8727a6cb> X-ATTACHMENT-NUM: 0 X-DNS-TYPE: 0 Subject: Re: [RFC PATCH] mmc: dw_mmc: remove redundant num_slots check To: Jaehoon Chung , Ulf Hansson References: <1453362769-16223-1-git-send-email-shawn.lin@rock-chips.com> <56A19811.9000101@samsung.com> Cc: shawn.lin@rock-chips.com, linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org From: Shawn Lin Message-ID: <56A19CDE.3090401@rock-chips.com> Date: Fri, 22 Jan 2016 11:07:10 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: <56A19811.9000101@samsung.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2016/1/22 10:46, Jaehoon Chung wrote: > Hi, Shawn. > > On 01/21/2016 04:52 PM, Shawn Lin wrote: >> num_slots comes from pdata if existing, otherwise from >> dw_mci_parse_dt which make it at least one slot. If >> num_slots is less than 1 for the existing pdata case, >> current code return -ENODEV. But dw_mci_probe seems to >> treat this a optional case as it will call SDMMC_GET_SLOT_NUM >> if no slot assigned. > > Well, we need to consider more thing.. > Host can get the number of slot from SDMMC_GET_SLOT_NUM(). > But i think this way also has the problem. > > num_slot isn't defined anywhere, and num_slot should be set to value of SDMMC_GET_SLOT_NUM. > If that value is higher than 1, it should be blocking..(I didn't test all cases..) > Actually, from the code itself, it confused me the way about how we get num_slot. At leaset, we might should try to cleanup it someway to make it a little more clear. And just as what you point out, we see some broblem here. > Even though this patch is not correct, i could check the problem relevant to num_slot, because of this patch. :) > Nice to here that. I make it a RFC patch since I also not quite sure about all cases including some corner cases. Let's think it twice. > my suggestion is if pdata->num_slot is not defined anywhere, just set to 1 by default. > not take from SDMMC_GET_SLOT_NUM. > yes, SDMMC_GET_SLOT_NUM is the capability of controller, num_slot is hardware wired number. So, geting it from SDMMC_GET_SLOT_NUM has problem. > if (host->pdata->nums_slots < 1 || > host->pdata->nums_slots > SDMMC_GET_SLOT_NUM()) > > This is correct condition. num_slots can't be higher than number of supported slots. > how about? Seems reasonable. I guess you want to come up with a new patch dealing with it? :) > > Best Regards, > Jaehoon Chung > >> >> Signed-off-by: Shawn Lin >> >> --- >> >> drivers/mmc/host/dw_mmc.c | 6 ------ >> 1 file changed, 6 deletions(-) >> >> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c >> index 7128351..a116ec6 100644 >> --- a/drivers/mmc/host/dw_mmc.c >> +++ b/drivers/mmc/host/dw_mmc.c >> @@ -2949,12 +2949,6 @@ int dw_mci_probe(struct dw_mci *host) >> } >> } >> >> - if (host->pdata->num_slots < 1) { >> - dev_err(host->dev, >> - "Platform data must supply num_slots.\n"); >> - return -ENODEV; >> - } >> - >> host->biu_clk = devm_clk_get(host->dev, "biu"); >> if (IS_ERR(host->biu_clk)) { >> dev_dbg(host->dev, "biu clock not available\n"); >> > > > > -- Best Regards Shawn Lin