Re: [bug report] drm/msm: dsi: Handle dual-channel for 6G as well

Jessica Zhang <quic_jesszhan@xxxxxxxxxxx> · Fri, 15 Oct 2021 12:34:20 -0700

Hey Dmitry,

On 10/15/2021 11:24 AM, Dmitry Baryshkov wrote:
On Fri, 15 Oct 2021 at 04:43, Jessica Zhang <jesszhan@xxxxxxxxxxxxxx> wrote:
Hey Dan,

On 10/1/2021 5:31 AM, Dan Carpenter wrote:
Hello Sean Paul,

The patch a6bcddbc2ee1: "drm/msm: dsi: Handle dual-channel for 6G as
well" from Jul 25, 2018, leads to the following
Smatch static checker warning:

       drivers/gpu/drm/msm/dsi/dsi_host.c:729 dsi_calc_clk_rate_6g()
       warn: wrong type for 'msm_host->esc_clk_rate' (should be 'ulong')

drivers/gpu/drm/msm/dsi/dsi_host.c
      721 int dsi_calc_clk_rate_6g(struct msm_dsi_host *msm_host, bool is_bonded_dsi)
      722 {
      723         if (!msm_host->mode) {
      724                 pr_err("%s: mode not set\n", __func__);
      725                 return -EINVAL;
      726         }
      727
      728         dsi_calc_pclk(msm_host, is_bonded_dsi);
--> 729         msm_host->esc_clk_rate = clk_get_rate(msm_host->esc_clk);
                  ^^^^^^^^^^^^^^^^^^^^^^
I don't know why Smatch is suddenly warning about ancient msm code, but
clock rates should be unsigned long.  (I don't remember why).

      730         return 0;
      731 }
I'm unable to recreate the warning with Smatch. After running
build_kernel_data.sh, I ran `<path to smatch>/smatch_scripts/kchecker
drivers/gpu/drm/msm/dsi/dsi_host.c` and got the following output:

CHECK scripts/mod/empty.c
CALL scripts/checksyscalls.sh
CALL scripts/atomic/check-atomics.sh
CHECK arch/arm64/kernel/vdso/vgettimeofday.c
CC drivers/gpu/drm/msm/dsi/dsi_host.o
CHECK drivers/gpu/drm/msm/dsi/dsi_host.c
drivers/gpu/drm/msm/dsi/dsi_host.c:2380 msm_dsi_host_power_on() warn:
missing error code 'ret'

Is there a specific .config you're using (that's not the default
mainline defconfig)? If so, can you please share it?
Are you running your checks with ARM32 or ARM64 in mind?
Note, esc_clk_rate is u32, while clk_get_rate()'s returns unsigned long.
It would make sense to change all three clocks rates in msm_dsi_host
struct (and several places where they are used) to unsigned long.

Thanks for the response. I'm aware of what's causing this issue and how 
to fix it, but I want to also be able to recreate the warning locally 
with Smatch.

Thanks,

Jessica Zhang

Thanks,

Jessica Zhang

regards,
dan carpenter