Hi,
On 25-08-15 14:05, Ulf Hansson wrote:
On 1 August 2015 at 11:01, Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
Hi,
On 21-07-15 14:15, Ulf Hansson wrote:
On 10 July 2015 at 17:14, Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
Some sdio wifi modules have not been working reliable with the sunxi-mmc
host code. This turns out to be caused by it starting new commands while
the card signals that it is still busy processing a previous command.
Which are those commands?
The code were things get stuck when not waiting for the busy signal uses
the following sdio helper functions:
sdio_readb/sdio_writeb
sdio_f0_readb/sdio_f0_writeb
sdio_readw/sdio_writew
sdio_readl/sdio_writel
sdio_readsb
sdio_memcpy_fromio/sdio_memcpy_toio
And directly issues the following command:
mmc_dat.flags = write ? MMC_DATA_WRITE : MMC_DATA_READ;
mmc_cmd.opcode = SD_IO_RW_EXTENDED;
mmc_cmd.arg = write ? 1<<31 : 0; /* write flag */
mmc_cmd.arg |= (fn & 0x7) << 28; /* SDIO func num */
mmc_cmd.arg |= 1<<27; /* block mode */
/* for function 1 the addr will be incremented */
mmc_cmd.arg |= (fn == 1) ? 1<<26 : 0;
mmc_cmd.flags = MMC_RSP_SPI_R5 | MMC_RSP_R5 | MMC_CMD_ADTC;
I do not know if the busy wait is necessary for all
of these, but the hack in the android kernel code,
which inserts calls to a wait_card_busy function directly
into: drivers/net/wireless/brcm80211/brcmfmac/bcmsdh.c
Does so for all of these.
Or more interesting, which response types do
these commands expect?
I don't think this is a sunxi specific issue, I have seen similar
issues for other host controllers.
Agreed, recent dw-mmc patches address the same issue, also involving
broadcom sdio wifi chips.
I am thinking that perhaps this should be managed by the mmc core
instead of local hacks to sunxi. Potentially we could make the core to
invoke the already existing host_ops->card_busy() callback when
needed...
I'm fine with solving this either way, implementing host_ops->card_busy()
for sunxi is easy, and if the core os modified to call that function
before issue sdio io ops (which seems to be the common thing here),
then that indeed is better then having the sunxi code always do
the busy check.
Okay, so let's make the core to call the ->card_busy() callback and
then it's up to each host driver to implement that callback.
Ok, do you plan to do a patch for this, or do you expect to get
one submitted to you ?
Regards,
Hans
As an optimization, we might consider (in a separate step) to add
MMC_RSP_BUSY to the response type. I realize that would somewhat be a
violation of the spec, but apparently the SDIO spec isn't really clear
on this area.
Within this context, could I ask whether you controller supports IRQ
based HW-busy detection? Or you need polling of the status register?
I'm afraid that we need to poll the status register. I've been unable
to find an irq flag corresponding to this.
Okay, thanks for the info.
[...]
Kind regards
Uffe
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