From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jaehoon Chung Subject: Re: [PATCH v5 3/4] mmc: dw_mmc: Cleanup disable of low power mode w/ SDIO interrupts Date: Wed, 03 Dec 2014 10:19:06 +0900 Message-ID: <547E650A.9050807@samsung.com> References: <1417563767-32181-1-git-send-email-dianders@chromium.org> <1417563767-32181-4-git-send-email-dianders@chromium.org> <547E569C.3080606@samsung.com> <547E6201.1090804@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Received: from mailout3.samsung.com ([203.254.224.33]:31862 "EHLO mailout3.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750952AbaLCBTJ (ORCPT ); Tue, 2 Dec 2014 20:19:09 -0500 In-reply-to: Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: Doug Anderson Cc: Seungwon Jeon , Ulf Hansson , Alim Akhtar , Sonny Rao , Andrew Bresticker , Heiko Stuebner , Chris Ball , "linux-mmc@vger.kernel.org" , "linux-kernel@vger.kernel.org" Doug. On 12/03/2014 10:12 AM, Doug Anderson wrote: > Jaehoon, > > On Tue, Dec 2, 2014 at 5:06 PM, Jaehoon Chung wrote: >> Hi Doug >> >> On 12/03/2014 09:36 AM, Doug Anderson wrote: >>> Jaehoon, >>> >>> On Tue, Dec 2, 2014 at 4:17 PM, Jaehoon Chung wrote: >>>>> @@ -1245,27 +1246,37 @@ static int dw_mci_get_cd(struct mmc_host *mmc) >>>>> return present; >>>>> } >>>>> >>>>> -/* >>>>> - * Disable lower power mode. >>>>> - * >>>>> - * Low power mode will stop the card clock when idle. According to the >>>>> - * description of the CLKENA register we should disable low power mode >>>>> - * for SDIO cards if we need SDIO interrupts to work. >>>>> - * >>>>> - * This function is fast if low power mode is already disabled. >>>>> - */ >>>>> -static void dw_mci_disable_low_power(struct dw_mci_slot *slot) >>>>> +static void dw_mci_init_card(struct mmc_host *mmc, struct mmc_card *card) >>>>> { >>>>> + struct dw_mci_slot *slot = mmc_priv(mmc); >>>>> struct dw_mci *host = slot->host; >>>>> - u32 clk_en_a; >>>>> - const u32 clken_low_pwr = SDMMC_CLKEN_LOW_PWR << slot->id; >>>>> >>>>> - clk_en_a = mci_readl(host, CLKENA); >>>>> + /* >>>>> + * Low power mode will stop the card clock when idle. According to the >>>>> + * description of the CLKENA register we should disable low power mode >>>>> + * for SDIO cards if we need SDIO interrupts to work. >>>>> + */ >>>>> + if (mmc->caps & MMC_CAP_SDIO_IRQ) { >>>>> + const u32 clken_low_pwr = SDMMC_CLKEN_LOW_PWR << slot->id; >>>>> + u32 clk_en_a_old; >>>>> + u32 clk_en_a; >>>>> >>>>> - if (clk_en_a & clken_low_pwr) { >>>>> - mci_writel(host, CLKENA, clk_en_a & ~clken_low_pwr); >>>>> - mci_send_cmd(slot, SDMMC_CMD_UPD_CLK | >>>>> - SDMMC_CMD_PRV_DAT_WAIT, 0); >>>>> + clk_en_a_old = mci_readl(host, CLKENA); >>>>> + >>>>> + if (card->type == MMC_TYPE_SDIO || >>>>> + card->type == MMC_TYPE_SD_COMBO) { >>>>> + set_bit(DW_MMC_CARD_NO_LOW_PWR, &slot->flags); >>>>> + clk_en_a = clk_en_a_old & ~clken_low_pwr; >>>>> + } else { >>>> >>>> I wonder this point. When entered at this point? >>>> >>>> MMC_CAP_SDIO_IRQ is sdio capability. and card->type is also related with SDIO, isn't? >>> >>> Right. As I understand it: >>> >>> * You can certainly add MMC_CAP_SDIO_IRQ to an external card slot that >>> might have an MMC card, and SD card, or an SDIO card. You still want >>> the LOW_PWR mode for MMC/SD cards but don't want it for SDIO cards in >>> that case. >> >> Ok, I understood your purpose. >> Your mean is MMC_CAP_SIDO_IRQ can be set to MMC or SD...not only SDIO card. >> It's reasonable. >> But i think it doesn't need to set LOW_PWR_mode for SD/eMMC at here. it should be already set to Low-power mode. >> And SDIO case should not enter at here. > > Are you sure? What about if you plug in an SDIO card, then unplug it, > then plug in an SD card? Oh.. :) I missed this case. thank you for pointing out. I considered only non-removable case, it's stupid... Best Regards, Jaehoon Chung > >>> * If you don't set MMC_CAP_SDIO_IRQ then presumably you've got some >>> problem where the SDIO interrupt is broken on your board. That means >>> you're using polling mode to find interrupts. As I understand it that >>> would allow you to use LOW_PWR since you don't need to detect SDIO >>> interrupts. I know on Marvell WiFi modules I tested this seemed to >>> work OK, but I doubt anyone is really running a production device in >>> this way. >> >> No, we needs to set MMC_CAP_SDIO_IRQ, if i didn't set to it, i will also see the problem. >> Since I knew which slot is used as SDIO card, i thought MMC_CAP_SDIO_IRQ is set for only sdio card. >> Then it would be check the twice whether card is SDIO or not. >> >> Actually, i didn't test WiFi module with this patch. but concept is not problem. > > Yup, I think you were only thinking about the embedded case where you > know that an SDIO card will be plugged into the slot. In the case > where you have an exposed slot it is certainly possible to expect > someone might plug in an SD card or an SDIO card. ...or even a combo > card! > > -Doug >