Re: [PATCH] MMC: OMAP: fix broken MMC on OMAP15XX/OMAP5912/OMAP310

[Ladislav Michl]

Aaro,

On Sun, Nov 18, 2018 at 10:19:19PM +0200, Aaro Koskinen wrote:
> Since v2.6.22 or so there has been reports [1] about OMAP MMC being
> broken on OMAP15XX based hardware (OMAP5912 and OMAP310). The breakage
> seems to have been caused by commit 46a6730e3ff9 ("mmc-omap: Fix
> omap to use MMC_POWER_ON") that changed clock enabling to be done
> on MMC_POWER_ON. This can happen multiple times in a row, and on 15XX
> the hardware doesn't seem to like it and the MMC just stops responding.
> Fix by memorizing the power mode and do the init only when necessary.

I'm going to use this patch as an argument against anybody complaining
kernel bugs do not get fixed. People just need to teach themselves to
be patient.

Tested-by: Ladislav Michl <ladis@xxxxxxxxxxxxxx>

> Before the patch (on Palm TE):
> 
> 	mmc0: new SD card at address b368
> 	mmcblk0: mmc0:b368 SDC   977 MiB
> 	mmci-omap mmci-omap.0: command timeout (CMD18)
> 	mmci-omap mmci-omap.0: command timeout (CMD13)
> 	mmci-omap mmci-omap.0: command timeout (CMD13)
> 	mmci-omap mmci-omap.0: command timeout (CMD12) [x 6]
> 	mmci-omap mmci-omap.0: command timeout (CMD13) [x 6]
> 	mmcblk0: error -110 requesting status
> 	mmci-omap mmci-omap.0: command timeout (CMD8)
> 	mmci-omap mmci-omap.0: command timeout (CMD18)
> 	mmci-omap mmci-omap.0: command timeout (CMD13)
> 	mmci-omap mmci-omap.0: command timeout (CMD13)
> 	mmci-omap mmci-omap.0: command timeout (CMD12) [x 6]
> 	mmci-omap mmci-omap.0: command timeout (CMD13) [x 6]
> 	mmcblk0: error -110 requesting status
> 	mmcblk0: recovery failed!
> 	print_req_error: I/O error, dev mmcblk0, sector 0
> 	Buffer I/O error on dev mmcblk0, logical block 0, async page read
> 	 mmcblk0: unable to read partition table
> 
> After the patch:
> 
> 	mmc0: new SD card at address b368
> 	mmcblk0: mmc0:b368 SDC   977 MiB
> 	 mmcblk0: p1
> 
> The patch is based on a fix and analysis done by Ladislav Michl.
> 
> Tested on OMAP15XX/OMAP310 (Palm TE), OMAP1710 (Nokia 770)
> and OMAP2420 (Nokia N810).
> 
> [1] https://marc.info/?t=123175197000003&r=1&w=2
> 
> Fixes: 46a6730e3ff9 ("mmc-omap: Fix omap to use MMC_POWER_ON")
> Reported-by: Ladislav Michl <ladis@xxxxxxxxxxxxxx>
> Reported-by: Andrzej Zaborowski <balrogg@xxxxxxxxx>
> Signed-off-by: Aaro Koskinen <aaro.koskinen@xxxxxx>
> ---
>  drivers/mmc/host/omap.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mmc/host/omap.c b/drivers/mmc/host/omap.c
> index adf32682f27a..c60a7625b1fa 100644
> --- a/drivers/mmc/host/omap.c
> +++ b/drivers/mmc/host/omap.c
> @@ -104,6 +104,7 @@ struct mmc_omap_slot {
>  	unsigned int		vdd;
>  	u16			saved_con;
>  	u16			bus_mode;
> +	u16			power_mode;
>  	unsigned int		fclk_freq;
>  
>  	struct tasklet_struct	cover_tasklet;
> @@ -1157,7 +1158,7 @@ static void mmc_omap_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
>  	struct mmc_omap_slot *slot = mmc_priv(mmc);
>  	struct mmc_omap_host *host = slot->host;
>  	int i, dsor;
> -	int clk_enabled;
> +	int clk_enabled, init_stream;
>  
>  	mmc_omap_select_slot(slot, 0);
>  
> @@ -1167,6 +1168,7 @@ static void mmc_omap_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
>  		slot->vdd = ios->vdd;
>  
>  	clk_enabled = 0;
> +	init_stream = 0;
>  	switch (ios->power_mode) {
>  	case MMC_POWER_OFF:
>  		mmc_omap_set_power(slot, 0, ios->vdd);
> @@ -1174,13 +1176,17 @@ static void mmc_omap_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
>  	case MMC_POWER_UP:
>  		/* Cannot touch dsor yet, just power up MMC */
>  		mmc_omap_set_power(slot, 1, ios->vdd);
> +		slot->power_mode = ios->power_mode;
>  		goto exit;
>  	case MMC_POWER_ON:
>  		mmc_omap_fclk_enable(host, 1);
>  		clk_enabled = 1;
>  		dsor |= 1 << 11;
> +		if (slot->power_mode != MMC_POWER_ON)
> +			init_stream = 1;
>  		break;
>  	}
> +	slot->power_mode = ios->power_mode;
>  
>  	if (slot->bus_mode != ios->bus_mode) {
>  		if (slot->pdata->set_bus_mode != NULL)
> @@ -1196,7 +1202,7 @@ static void mmc_omap_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
>  	for (i = 0; i < 2; i++)
>  		OMAP_MMC_WRITE(host, CON, dsor);
>  	slot->saved_con = dsor;
> -	if (ios->power_mode == MMC_POWER_ON) {
> +	if (init_stream) {
>  		/* worst case at 400kHz, 80 cycles makes 200 microsecs */
>  		int usecs = 250;
>  
> @@ -1234,6 +1240,7 @@ static int mmc_omap_new_slot(struct mmc_omap_host *host, int id)
>  	slot->host = host;
>  	slot->mmc = mmc;
>  	slot->id = id;
> +	slot->power_mode = MMC_POWER_UNDEFINED;
>  	slot->pdata = &host->pdata->slots[id];
>  
>  	host->slots[id] = slot;
> -- 
> 2.17.0