From mboxrd@z Thu Jan 1 00:00:00 1970 From: Giulio Benetti Date: Tue, 23 Feb 2021 01:25:53 +0100 Subject: [PATCH v2] clk: fix clk_get_rate() documentation In-Reply-To: References: Message-ID: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On 2/22/21 8:13 PM, Heinrich Schuchardt wrote: > On 2/14/21 4:49 AM, Jesse T wrote: >> Awesome, thanks! I must have forgotten how twos complement works for a >> sec... >> >> On Sat, Feb 13, 2021 at 10:17 PM Giulio Benetti < >> giulio.benetti at benettiengineering.com> wrote: >> >>> Hi Jesse, >>> >>> Il giorno 14 feb 2021, alle ore 03:58, Jesse T >>> ha scritto: >>> >>> ? >>> This looks good to me, and helps beginners like me. As for the function >>> itself, i have 2 concerns: If it does return a negative value why is it >>> unsigned, if it is in fact signed that a clock above 2.2Ghz is a negative >>> number. >>> >>> >>> I was worried too at first sight but if you try to check negative numbers >>> you see that -1 is 0xFFFFFFFF so in the worst case you only loose 4095 >>> numbers from the maximum, try to check with hex calculator. And that is the >>> trick. >>> >>> As for the IS_ERR_VALUE macro there still is a chance that it will error >>> if the clock just so happens to be 2^31 through 2^31 + number of err >>> values. >>> >>> >>> This is answered from above and IS_ERR_VALUE is a very contracted macro >>> that basically let you to keep value NOT valid if (0 > value > 4095). >>> >>> Just voicing my concerns i assume as i learn more about uboot, >>> linux,rtos's and different programs there will be minor issues like this. >>> >>> >>> Sure, no problem :-) >>> >>> Giulio >>> >>> >>> On Sat, Feb 13, 2021 at 9:17 PM Giulio Benetti < >>> giulio.benetti at benettiengineering.com> wrote: >>> >>>> Improve clk_get_rate() @return documentation that otherwise is a bit >>>> ambiguous. At the moment I expect to return 0 as error since the return >>>> type is 'ulong', instead the function really returns negative value in >>>> case the corresponding function pointer is null and returns 0 if the clock >>>> is invalid. >>>> >>>> Signed-off-by: Giulio Benetti >>>> --- >>>> V1->V2: >>>> * previous comment was wrong, this function returns negative value, so >>>> let's >>>> improve it's @return documentation as suggested by Simon Glass >>>> --- >>>> include/clk.h | 3 ++- >>>> 1 file changed, 2 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/include/clk.h b/include/clk.h >>>> index ca6b85fa6f..5a8c7244d0 100644 >>>> --- a/include/clk.h >>>> +++ b/include/clk.h >>>> @@ -344,7 +344,8 @@ int clk_free(struct clk *clk); >>>> * >>>> * @clk: A clock struct that was previously successfully requested >>>> by >>>> * clk_request/get_by_*(). >>>> - * @return clock rate in Hz, or -ve error code. >>>> + * @return clock rate in Hz on success, 0 for invalid clock, or -ve >>>> error code >>>> + * for other errors. >>>> */ >>>> ulong clk_get_rate(struct clk *clk); >>>> >>>> -- >>>> 2.25.1 >>>> >>>> > > Cc: Lukasz Majewski > Lukasz is maintainer for CLOCK. Ah thank you that's right. I've missed it because ./scripts/get_maintainer.pl didn't list him. -- Giulio Benetti Benetti Engineering sas