Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752818Ab0KIH3j (ORCPT ); Tue, 9 Nov 2010 02:29:39 -0500 Received: from sm-d311v.smileserver.ne.jp ([203.211.202.206]:36964 "EHLO sm-d311v.smileserver.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752284Ab0KIH3g (ORCPT ); Tue, 9 Nov 2010 02:29:36 -0500 Message-ID: <004801cb7fdf$dbd27af0$66f8800a@maildom.okisemi.com> From: "Tomoya MORINAGA" To: "Kyungmin Park" Cc: , , "Andrew\"" , References: <4CD8DE9C.4040505@dsn.okisemi.com> Subject: Re: A MMC card transfer issue Date: Tue, 9 Nov 2010 16:29:34 +0900 MIME-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1983 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1983 X-Hosting-Pf: 0 X-NAI-Spam-Score: 1.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3982 Lines: 111 Hi Park, Thank you for your information. I will try it soon. Thanks, Tomoya MORINAGA OKI SEMICONDUCTOR CO., LTD. ----- Original Message ----- From: "Kyungmin Park" To: "Tomoya MORINAGA" Cc: ; ; "Andrew"" ; Sent: Tuesday, November 09, 2010 2:53 PM Subject: Re: A MMC card transfer issue > 2010/11/9 Tomoya MORINAGA : > > I am facing the issue about some MMC cards on Intel EG20T PCH (Platform Controller Hub). > > The linux version is 2.6.36. > > I can not transfer data the MMC cards (e.g. Transcned MMC card). > > The card is 1 bit bus width. And the card is according to MMC specification V3.x. > > And the EG20T has a 4 bit bus width capability > > Linux MMC standard driver decides the card bus width as 4 bit, > > if the MMC specification version is larger than or equal to V4.0 like below. > > > > linux/drivers/mmc/core/mmc.c > > > > 505 /* > > 506 * Activate wide bus (if supported). > > 507 */ > > 508 if ((card->csd.mmca_vsn >= CSD_SPEC_VER_4) && > > 509 (host->caps & (MMC_CAP_4_BIT_DATA | MMC_CAP_8_BIT_DATA))) { > > 510 unsigned ext_csd_bit, bus_width; > > 511 > > 512 if (host->caps & MMC_CAP_8_BIT_DATA) { > > 513 ext_csd_bit = EXT_CSD_BUS_WIDTH_8; > > 514 bus_width = MMC_BUS_WIDTH_8; > > 515 } else { > > 516 ext_csd_bit = EXT_CSD_BUS_WIDTH_4; > > 517 bus_width = MMC_BUS_WIDTH_4; > > 518 } > > 519 > > 520 err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL, > > 521 EXT_CSD_BUS_WIDTH, ext_csd_bit); > > 522 > > 523 if (err && err != -EBADMSG) > > 524 goto free_card; > > 525 > > 526 if (err) { > > 527 printk(KERN_WARNING "%s: switch to bus width %d " > > 528 "failed\n", mmc_hostname(card->host), > > 529 1 << bus_width); > > 530 err = 0; > > 531 } else { > > 532 mmc_set_bus_width(card->host, bus_width); > > 533 } > > 534 } > > 535 > > > > However the MMC specification version id is the same as V3.x and V4.0. > > Therefore the driver uses the 4 bit bus width for the MMC card > > even if the card has only 1 bit bus width. > > I modified the driver to use 1 bit bus width only tentatively and confirmed that > > we can mount the card and R/W correctly. > > > > I think we can not support MMC_CAP_4_BIT_DATA or MMC_CAP_8_BIT_DATA in MMC V4.0. > > > > How do you think ? > > You can find a patch for 4-bit support. the problem is there's some > bug related so it set the 4 & 8 bit support both. > So line 512 is always true. you can just remove the one line like this. > > It's quirk-and-dirty patch. now we try to find a generic solution to > solve this issue. > --- a/drivers/mmc/host/sdhci.c > +++ b/drivers/mmc/host/sdhci.c > @@ -1849,7 +1849,7 @@ int sdhci_add_host(struct sdhci_host *host) > mmc->caps |= MMC_CAP_SDIO_IRQ; > > if (!(host->quirks & SDHCI_QUIRK_FORCE_1_BIT_DATA)) > - mmc->caps |= MMC_CAP_4_BIT_DATA | MMC_CAP_8_BIT_DATA; > + mmc->caps |= MMC_CAP_4_BIT_DATA; > > if (caps & SDHCI_CAN_DO_HISPD) > mmc->caps |= MMC_CAP_SD_HIGHSPEED | MMC_CAP_MMC_HIGHSPEED; > > Thank you, > Kyungmin Park > > > > -- > > Thanks, > > Tomoya MORINAGA(OKI SEMICONDUCTOR CO., LTD.) > > -- > > 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 > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/