> -----Original Message----- > From: Adrian Hunter [mailto:adrian.hunter@xxxxxxxxx] > Sent: Wednesday, October 13, 2010 4:58 PM > To: Dong, Chuanxiao > Cc: linux-mmc@xxxxxxxxxxxxxxx; Gao, Yunpeng > Subject: Re: mmc_core: question on mmc_do_erase function > > On 13/10/10 11:35, Dong, Chuanxiao wrote: > >> -----Original Message----- > >> From: Adrian Hunter [mailto:adrian.hunter@xxxxxxxxx] > >> Sent: Wednesday, October 13, 2010 3:56 PM > >> To: Dong, Chuanxiao > >> Cc: linux-mmc@xxxxxxxxxxxxxxx; Gao, Yunpeng > >> Subject: Re: mmc_core: question on mmc_do_erase function > >> > >> On 12/10/10 16:11, Dong, Chuanxiao wrote: > >>> Hi adrian > >>> > >>> I got some questions about MMC driver erase function. Help you can > >>> give me some suggestion. My host controller is a kind of SDHCI host > >>> controller. And testing below code by using HD micro SD card. > >>> + memset(&cmd, 0, sizeof(struct mmc_command)); > >>> + cmd.opcode = MMC_ERASE; > >>> + cmd.arg = arg; > >>> + cmd.flags = MMC_RSP_SPI_R1B | MMC_RSP_R1B | MMC_CMD_AC; > >>> + mmc_set_erase_timeout(card,&cmd, arg, qty); > >>> + err = mmc_wait_for_cmd(card->host,&cmd, 0); > >>> + if (err) { > >>> + printk(KERN_ERR "mmc_erase: erase error %d, status %#x\n", > >>> + err, cmd.resp[0]); > >>> + err = -EIO; > >>> + goto out; > >>> + } > >>> As MMC 4.4 standard said, CMD38 need R1B response. So when SDHCI host > >>> controller got a SDHCI_INT_RESPONSE interrupt, driver will ignore > >>> this and keep on waiting for a SDHCI_INT_DATA_END interrupt to finish > >>> MMC_ERASE command. Then I got problems....My host controller will got > >>> a DATA_TIMEOUT interrupt if host controller cannot generate any > >>> interrupt during its waiting time, unfortunately the max waiting time > >>> for my SDHCI host controller is 5s. > >> > >> I don't know SDHCI. Can you disable the timeout altogether and use a > >> timer? > >> > > OK, thanks. If hardware can disable the timeout interrupt, I will try > > use a timer. But if the host controllers cannot disable the their > > timeout interrupt, what should they do? > > The block driver currently sets max_discard_sectors to UINT_MAX i.e. > unlimited. This could instead be based on a value from the driver > in the same way that max_sectors is. Refer to mmc_init_queue() > in card/queue.c OK, thanks for your help, Adrian. > > > >>> So if any ERASE operation need > >>> more than 5s seconds to finish, my controller will not finish the > >>> ERASE operation and only generate a DATA_TIMEOUT interrupt. The ERASE > >>> will be failed. Another, MMC driver also has a 10s timer to keep > >>> watch over the interrupt, if ERASE operation need more than 10s to > >>> finish, this timer also can report a TIMEOUT error. I think > >>> cmd->erase_timeout can help to set the timer expires, but how to deal > >>> with this issue for SDHCI host controller? How about split ERASE > >>> groups to be smaller ones? > >> > >> Where is the erase coming from? A file system? The discard ioctl? > > Erase command comes from the discard ioctl. > > > >> It is possible to set a maximum size for the discard but it pays > >> no attention to alignment, so you can get very sub-optimal erases. > > > > -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
