On Wed, Feb 19, 2020 at 9:10 AM Ondrej Jirman <[email protected]> wrote: > > When doing a 16-bit read that returns data in the MSB byte, the > RSB_DATA register will keep the MSB byte unchanged when doing > the following 8-bit read. sunxi_rsb_read() will then return > a result that contains high byte from 16-bit read mixed with > the 8-bit result. > > The consequence is that after this happens the PMIC's regmap will > look like this: (0x33 is the high byte from the 16-bit read) > > % cat /sys/kernel/debug/regmap/sunxi-rsb-3a3/registers > 00: 33 > 01: 33 > 02: 33 > 03: 33 > 04: 33 > 05: 33 > 06: 33 > 07: 33 > 08: 33 > 09: 33 > 0a: 33 > 0b: 33 > 0c: 33 > 0d: 33 > 0e: 33 > [snip] > > Fix this by masking the result of the read with the correct mask > based on the size of the read. There are no 16-bit users in the > mainline kernel, so this doesn't need to get into the stable tree. > > Signed-off-by: Ondrej Jirman <[email protected]>
Acked-by: Chen-Yu Tsai <[email protected]> for the fix, however it's not entirely clear to me how the MSB 0x33 value got into the regmap. Looks like I expected the regmap core to handle any overflows, or didn't expect the lingering MSB from 16-bit reads, as I didn't have any 16-bit register devices back when I wrote this. ChenYu > --- > drivers/bus/sunxi-rsb.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/drivers/bus/sunxi-rsb.c b/drivers/bus/sunxi-rsb.c > index b8043b58568ac..8ab6a3865f569 100644 > --- a/drivers/bus/sunxi-rsb.c > +++ b/drivers/bus/sunxi-rsb.c > @@ -316,6 +316,7 @@ static int sunxi_rsb_read(struct sunxi_rsb *rsb, u8 > rtaddr, u8 addr, > { > u32 cmd; > int ret; > + u32 mask; > > if (!buf) > return -EINVAL; > @@ -323,12 +324,15 @@ static int sunxi_rsb_read(struct sunxi_rsb *rsb, u8 > rtaddr, u8 addr, > switch (len) { > case 1: > cmd = RSB_CMD_RD8; > + mask = 0xffu; > break; > case 2: > cmd = RSB_CMD_RD16; > + mask = 0xffffu; > break; > case 4: > cmd = RSB_CMD_RD32; > + mask = 0xffffffffu; > break; > default: > dev_err(rsb->dev, "Invalid access width: %zd\n", len); > @@ -345,7 +349,7 @@ static int sunxi_rsb_read(struct sunxi_rsb *rsb, u8 > rtaddr, u8 addr, > if (ret) > goto unlock; > > - *buf = readl(rsb->regs + RSB_DATA); > + *buf = readl(rsb->regs + RSB_DATA) & mask; > > unlock: > mutex_unlock(&rsb->lock); > -- > 2.25.1 > -- You received this message because you are subscribed to the Google Groups "linux-sunxi" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/linux-sunxi/CAGb2v67BLODmDmQOJH-m-KWVtXS2EGrnPxi9czj6oipHPDTfjw%40mail.gmail.com.
