Re: [PATCH 1/2] bus: mhi: core: Fix parsing of mhi_flags

From: Hemant Kumar
Date: Thu Apr 16 2020 - 15:02:20 EST


Hi Mani,

On 4/13/20 5:07 AM, Manivannan Sadhasivam wrote:
With the current parsing of mhi_flags, the following statement always
return false:

eob = !!(flags & MHI_EOB);

This is due to the fact that 'enum mhi_flags' starts with index 0 and we
are using direct AND operation to extract each bit. Fix this by using
BIT() macro to extract each bit and make the mhi_flags index start from 1.

Fixes: 189ff97cca53 ("bus: mhi: core: Add support for data transfer")
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
---
drivers/bus/mhi/core/main.c | 6 +++---
include/linux/mhi.h | 2 +-
2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
index eb4256b81406..4165a853c189 100644
--- a/drivers/bus/mhi/core/main.c
+++ b/drivers/bus/mhi/core/main.c
@@ -1090,9 +1090,9 @@ int mhi_gen_tre(struct mhi_controller *mhi_cntrl, struct mhi_chan *mhi_chan,
if (ret)
return ret;
- eob = !!(flags & MHI_EOB);
- eot = !!(flags & MHI_EOT);
- chain = !!(flags & MHI_CHAIN);
+ eob = !!(flags & BIT(0));
+ eot = !!(flags & BIT(1));
+ chain = !!(flags & BIT(2));

How about setting enums with BIT macro and still use same enums above. If flags is having MHI _CHAIN (enum value 3) but comparing with BIT(2) (value 4) will not work.

bei = !!(mhi_chan->intmod);
mhi_tre = tre_ring->wp;
diff --git a/include/linux/mhi.h b/include/linux/mhi.h
index ad1996001965..22185fecbbf2 100644
--- a/include/linux/mhi.h
+++ b/include/linux/mhi.h
@@ -53,7 +53,7 @@ enum mhi_callback {
* @MHI_CHAIN: Linked transfer
*/
enum mhi_flags {
- MHI_EOB,
+ MHI_EOB = 1,
MHI_EOT,
MHI_CHAIN,
};

enum mhi_flags {

ÂÂÂ MHI_EOB = BIT(0),

ÂÂÂ MHI_EOT = BIT(1),

ÂÂÂ MHI_CHAIN = BIT(2),

}

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