From mboxrd@z Thu Jan 1 00:00:00 1970 From: dirk.behme@de.bosch.com (Dirk Behme) Date: Thu, 26 Jul 2012 10:06:08 +0200 Subject: Devicetree: Initialization order of mmc block devices? In-Reply-To: <201207191313.46178.arnd@arndb.de> References: <5006571A.7060103@de.bosch.com> <201207191313.46178.arnd@arndb.de> Message-ID: <5010FA70.3080306@de.bosch.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 19.07.2012 15:13, Arnd Bergmann wrote: > On Wednesday 18 July 2012, Dirk Behme wrote: >> Any idea how we could influence the initialization order of the mmc >> block devices using a DT based kernel? Ensuring that the internal, hard >> wired mmc card is always mapped to mmcblk0? > > I think the best solution would be to parse the "/aliases" device node > and look for an "mmc0" or "mmc1" property with a phandle to the respective > device. That's how we sort the serial ports. We have the of_alias_get_id() > function to pick out a node from there, so it should be possible to use > that in the mmc core similar to how we use it in the uart drivers. Looking at the serial example you mentioned and trying to adapt that for mmcblkX I tried something like below [1] on a Freescale i.MX6 board and it seems to work :) Is this what you had in mind? While I think the DT/of_alias_get_id() part looks ok (?), the way of passing the retrieved value from the driver sdhci-esdhc-imx.c to the block.c is quite hackish. I took it from the examples how this was hacked in the past. Is there any better way of passing the information read in the driver by of_alias_get_id() to block.c? With the value read by of_alias_get_id() we somehow have to set name_idx in block.c. Best regards Dirk [1] Just fyi: From hardware point of view, usdhc1 connects the removable SD card, while usdhc3 attaches the non-removable eMMC. With the alias, independent if the SD card is there or not, the eMMC becomes always mmcblk1. And this is what we like to achieve here. --- arch/arm/boot/dts/imx6q-sabrelite.dts | 5 +++++ arch/arm/plat-mxc/include/mach/esdhc.h | 1 + drivers/mmc/card/block.c | 6 ++++-- drivers/mmc/host/sdhci-esdhc-imx.c | 14 ++++++++++++++ include/linux/mmc/host.h | 3 +++ 5 files changed, 27 insertions(+), 2 deletions(-) Index: a/arch/arm/boot/dts/imx6q-sabrelite.dts =================================================================== --- a/arch/arm/boot/dts/imx6q-sabrelite.dts +++ b/arch/arm/boot/dts/imx6q-sabrelite.dts @@ -18,6 +18,11 @@ model = "Freescale i.MX6 Quad sabrelite Sample Board"; compatible = "fsl,imx6q-sabrelite", "fsl,imx6q"; + aliases { + mmcblk0 = &usdhc1; + mmcblk1 = &usdhc3; + }; + memory { reg = <0x10000000 0x40000000>; }; Index: freescale-linux-2.6-imx.git/drivers/mmc/host/sdhci-esdhc-imx.c =================================================================== --- a/drivers/mmc/host/sdhci-esdhc-imx.c +++ b/drivers/mmc/host/sdhci-esdhc-imx.c @@ -447,10 +447,21 @@ sdhci_esdhc_imx_probe_dt(struct platform struct esdhc_platform_data *boarddata) { struct device_node *np = pdev->dev.of_node; + int ret; if (!np) return -ENODEV; + ret = of_alias_get_id(np, "mmcblk"); + if (ret < 0) { + dev_err(&pdev->dev, "failed to get alias id, errno %d\n", ret); + return -ENODEV; + } + + boarddata->devidx = ret; + if (of_get_property(np, "fsl,card-wired", NULL)) boarddata->cd_type = ESDHC_CD_PERMANENT; @@ -581,6 +592,9 @@ static int __devinit sdhci_esdhc_imx_pro host->mmc->parent->platform_data); } + /* copy mmc block device index */ + host->mmc->devidx = boarddata->devidx; + /* write_protect */ if (boarddata->wp_type == ESDHC_WP_GPIO) { err = gpio_request_one(boarddata->wp_gpio, GPIOF_IN, "ESDHC_WP"); Index: a/arch/arm/plat-mxc/include/mach/esdhc.h =================================================================== --- a/arch/arm/plat-mxc/include/mach/esdhc.h +++ bt/arch/arm/plat-mxc/include/mach/esdhc.h @@ -41,5 +41,6 @@ struct esdhc_platform_data { enum wp_types wp_type; enum cd_types cd_type; int vdd_180; + unsigned int devidx; }; #endif /* __ASM_ARCH_IMX_ESDHC_H */ Index: freescale-linux-2.6-imx.git/drivers/mmc/card/block.c =================================================================== --- a/drivers/mmc/card/block.c +++ b/drivers/mmc/card/block.c @@ -1466,7 +1466,8 @@ static struct mmc_blk_data *mmc_blk_allo struct mmc_blk_data *md; int devidx, ret; - devidx = find_first_zero_bit(dev_use, max_devices); + devidx = find_next_zero_bit(dev_use, max_devices, + card->host->devidx); if (devidx >= max_devices) return ERR_PTR(-ENOSPC); __set_bit(devidx, dev_use); @@ -1484,7 +1485,8 @@ static struct mmc_blk_data *mmc_blk_allo * index anymore so we keep track of a name index. */ if (!subname) { - md->name_idx = find_first_zero_bit(name_use, max_devices); + md->name_idx = find_next_zero_bit(name_use, max_devices, + card->host->devidx); __set_bit(md->name_idx, name_use); } else md->name_idx = ((struct mmc_blk_data *) Index: a/include/linux/mmc/host.h =================================================================== --- a/include/linux/mmc/host.h +++ b/include/linux/mmc/host.h @@ -326,6 +326,9 @@ struct mmc_host { unsigned int actual_clock; /* Actual HC clock rate */ + /* preferred mmc block device index (mmcblkX) */ + unsigned int devidx; + unsigned long private[0] ____cacheline_aligned; };