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Date: Wed, 15 Dec 2010 07:41:18 +0100
From: Takashi Iwai <tiwai@...e.de>
To: zhangfei gao <zhangfei.gao@...il.com>
Cc: Chris Ball <cjb@...top.org>, linux-mmc@...r.kernel.org,
linux-kernel@...r.kernel.org, Aries Lee <arieslee@...cron.com>,
wuqm@...vell.com, Philip Rakity <prakity@...vell.com>
Subject: Re: [PATCH 2/2] mmc: Test bus-width for old MMC devices
At Tue, 14 Dec 2010 23:03:42 -0500,
zhangfei gao wrote:
>
> On Wed, Nov 24, 2010 at 1:21 AM, Takashi Iwai <tiwai@...e.de> wrote:
> > From: Aries Lee <arieslee@...cron.com>
> >
> > Some old MMC devices fail with the 4/8 bits the driver tries to use
> > exclusively. This patch adds a test for the given bus setup and falls
> > back to the lower bit mode (until 1-bit mode) when the test fails.
> >
> > [Major rework and refactoring by tiwai]
> >
> > Signed-off-by: Aries Lee <arieslee@...cron.com>
> > Signed-off-by: Takashi Iwai <tiwai@...e.de>
> > ---
> > drivers/mmc/core/mmc.c | 49 ++++++++++++---------
> > drivers/mmc/core/mmc_ops.c | 102 ++++++++++++++++++++++++++++++++++++++++++++
> > drivers/mmc/core/mmc_ops.h | 1 +
> > 3 files changed, 131 insertions(+), 21 deletions(-)
> >
> > diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> > index e81e6fe..5d8b4b2 100644
> > --- a/drivers/mmc/core/mmc.c
> > +++ b/drivers/mmc/core/mmc.c
> > @@ -507,29 +507,36 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
> > */
> > if ((card->csd.mmca_vsn >= CSD_SPEC_VER_4) &&
> > (host->caps & (MMC_CAP_4_BIT_DATA | MMC_CAP_8_BIT_DATA))) {
> > - unsigned ext_csd_bit, bus_width;
> > -
> > - if (host->caps & MMC_CAP_8_BIT_DATA) {
> > - ext_csd_bit = EXT_CSD_BUS_WIDTH_8;
> > - bus_width = MMC_BUS_WIDTH_8;
> > - } else {
> > - ext_csd_bit = EXT_CSD_BUS_WIDTH_4;
> > - bus_width = MMC_BUS_WIDTH_4;
> > + static unsigned ext_csd_bits[] = {
> > + EXT_CSD_BUS_WIDTH_8,
> > + EXT_CSD_BUS_WIDTH_4,
> > + EXT_CSD_BUS_WIDTH_1
> > + };
> > + static unsigned bus_widths[] = {
> > + MMC_BUS_WIDTH_8,
> > + MMC_BUS_WIDTH_4,
> > + MMC_BUS_WIDTH_1
> > + };
> > + unsigned idx;
> > +
> > + if (host->caps & MMC_CAP_8_BIT_DATA)
> > + idx = 0;
> > + else
> > + idx = 1;
> > + for (; idx < ARRAY_SIZE(bus_widths); idx++) {
> > + err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
> > + EXT_CSD_BUS_WIDTH, ext_csd_bits[idx]);
> > + if (!err) {
> > + mmc_set_bus_width(card->host, bus_widths[idx]);
> > + err = mmc_bus_test(card, bus_widths[idx]);
> > + if (!err)
> > + break;
> > + }
> > }
> > -
> > - err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
> > - EXT_CSD_BUS_WIDTH, ext_csd_bit);
> > -
> > - if (err && err != -EBADMSG)
> > - goto free_card;
> > -
> > if (err) {
> > - printk(KERN_WARNING "%s: switch to bus width %d "
> > - "failed\n", mmc_hostname(card->host),
> > - 1 << bus_width);
> > - err = 0;
> > - } else {
> > - mmc_set_bus_width(card->host, bus_width);
> > + printk(KERN_WARNING "%s: switch to bus width failed\n",
> > + mmc_hostname(card->host));
> > + goto free_card;
> > }
> > }
> >
> > diff --git a/drivers/mmc/core/mmc_ops.c b/drivers/mmc/core/mmc_ops.c
> > index 326447c..f8f47f9 100644
> > --- a/drivers/mmc/core/mmc_ops.c
> > +++ b/drivers/mmc/core/mmc_ops.c
> > @@ -462,3 +462,105 @@ int mmc_send_status(struct mmc_card *card, u32 *status)
> > return 0;
> > }
> >
> > +#define MMC_CMD_BUS_TEST_W 19
> > +#define MMC_CMD_BUS_TEST_R 14
> > +
> > +static int
> > +mmc_send_bus_test(struct mmc_card *card, struct mmc_host *host, u8 opcode,
> > + u8 len)
> > +{
> > + struct mmc_request mrq;
> > + struct mmc_command cmd;
> > + struct mmc_data data;
> > + struct scatterlist sg;
> > + u8 *data_buf;
> > + u8 *test_buf;
> > + int i, err;
> > + static u8 testdata_8bit[8] = { 0x55, 0xaa, 0, 0, 0, 0, 0, 0 };
> > + static u8 testdata_4bit[4] = { 0x5a, 0, 0, 0 };
> > +
> > + /* dma onto stack is unsafe/nonportable, but callers to this
> > + * routine normally provide temporary on-stack buffers ...
> > + */
> > + data_buf = kmalloc(len, GFP_KERNEL);
> > + if (!data_buf)
> > + return -ENOMEM;
> > +
> > + if (len == 8)
> > + test_buf = testdata_8bit;
> > + else if (len == 4)
> > + test_buf = testdata_4bit;
> > + else {
> > + printk(KERN_ERR "%s: Invaild bus_width %d\n",
> > + mmc_hostname(host), len);
> > + return -EINVAL;
> > + }
> > +
> > + if (opcode == MMC_CMD_BUS_TEST_W)
> > + memcpy(data_buf, test_buf, len);
> > +
> > + memset(&mrq, 0, sizeof(struct mmc_request));
> > + memset(&cmd, 0, sizeof(struct mmc_command));
> > + memset(&data, 0, sizeof(struct mmc_data));
> > +
> > + mrq.cmd = &cmd;
> > + mrq.data = &data;
> > + cmd.opcode = opcode;
> > + cmd.arg = 0;
> > +
> > + /* NOTE HACK: the MMC_RSP_SPI_R1 is always correct here, but we
> > + * rely on callers to never use this with "native" calls for reading
> > + * CSD or CID. Native versions of those commands use the R2 type,
> > + * not R1 plus a data block.
> > + */
> > + cmd.flags = MMC_RSP_SPI_R1 | MMC_RSP_R1 | MMC_CMD_ADTC;
> > +
> > + data.blksz = len;
> > + data.blocks = 1;
> > + if (opcode == MMC_CMD_BUS_TEST_R)
> > + data.flags = MMC_DATA_READ;
> > + else
> > + data.flags = MMC_DATA_WRITE;
> > +
> > + data.sg = &sg;
> > + data.sg_len = 1;
> > + sg_init_one(&sg, data_buf, len);
> > + mmc_wait_for_req(host, &mrq);
> > + err = 0;
> > + if (opcode == MMC_CMD_BUS_TEST_R) {
> > + for (i = 0; i < len / 4; i++)
> > + if ((test_buf[i] ^ data_buf[i]) != 0xff) {
> > + err = -EIO;
> > + break;
> > + }
> > + }
> > + kfree(data_buf);
> > +
> > + if (cmd.error)
> > + return cmd.error;
> > + if (data.error)
>
> if (data.error && (data.error != -EILSEQ))
> Could you add code here to ignore CRC error of CMD14.
> According to spec, CRC bits from card are optional in CMD14, and it is
> ignored by host.
> However some host still check and may get crc error here if card does not send.
Philip corrected my patch and added such a check (in sdhci.c side).
I'm going to resend the revised patch soon.
thanks,
Takashi
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