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 10:06:09 +0900 Message-ID: <547E6201.1090804@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> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Received: from mailout1.samsung.com ([203.254.224.24]:50786 "EHLO mailout1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750840AbaLCBGN (ORCPT ); Tue, 2 Dec 2014 20:06:13 -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" 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. > > * 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. Best Regards, Jaehoon Chung > > > Basically I was trying to mirror the functionality of the old code as > closely as possible. In the old code if you were using polling mode > then dw_mci_enable_sdio_irq() should never be called and you'd never > go out of low power mode. > > -Doug >