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charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi, On Thu, Feb 20, 2020 at 06:32:13PM +0100, Maxime Ripard wrote: > On Wed, Feb 19, 2020 at 02:09:50AM +0100, Ondrej Jirman 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 > > --- > > 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; > > Thanks for debugging this and the extensive commit log. > > I guess it would be cleaner to just use GENMASK(len * 8, 0) here? GENMASK most probably fails with value (32,0) I think. #define GENMASK(h, l) \ (((~UL(0)) - (UL(1) << (l)) + 1) & \ (~UL(0) >> (BITS_PER_LONG - 1 - (h)))) would give ~0 >> -1 regards, o. > Maxime _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel