From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sergei Shtylyov Subject: Re: [RFC 02/11] i2c: add quirk checks to core Date: Sat, 10 Jan 2015 00:05:07 +0300 Message-ID: <54B04283.5070705@cogentembedded.com> References: <1420824103-24169-1-git-send-email-wsa@the-dreams.de> <1420824103-24169-3-git-send-email-wsa@the-dreams.de> <54B02D7F.7040501@cogentembedded.com> <20150109204522.GB1904@katana> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20150109204522.GB1904@katana> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Wolfram Sang Cc: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linuxppc-dev-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, linux-mips-6z/3iImG2C8G8FEW9MqTrA@public.gmane.org, Benjamin Herrenschmidt , Ludovic Desroches , Yingjoe Chen , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-i2c@vger.kernel.org Hello. On 01/09/2015 11:45 PM, Wolfram Sang wrote: >>> Let the core do the checks if HW quirks prevent a transfer. Saves code >> >from drivers and adds consistency. >>> Signed-off-by: Wolfram Sang >>> --- >>> drivers/i2c/i2c-core.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++++++ >>> 1 file changed, 53 insertions(+) >>> >>> diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c >>> index 39d25a8cb1ad..7b10a19abf5b 100644 >>> --- a/drivers/i2c/i2c-core.c >>> +++ b/drivers/i2c/i2c-core.c >>> @@ -2063,6 +2063,56 @@ module_exit(i2c_exit); >>> * ---------------------------------------------------- >>> */ >>> >>> +/* Check if val is exceeding the quirk IFF quirk is non 0 */ >>> +#define i2c_quirk_exceeded(val, quirk) ((quirk) && ((val) > (quirk))) >>> + >>> +static int i2c_quirk_error(struct i2c_adapter *adap, struct i2c_msg *msg, char *err_msg) >>> +{ >>> + dev_err(&adap->dev, "quirk: %s (addr 0x%04x, size %u)\n", err_msg, msg->addr, msg->len); >>> + return -EOPNOTSUPP; >>> +} >> Always returning the same value doesn't make much sense. Are you trying >> to save space on the call sites? > Please elaborate. I think it does. If a quirk matches, we report that we > don't support this transfer. OK, but what's the point of having this function return *int* if it always returns the same value? AFAIU, you're trying to save the code space on the call sites of this function by not having *return* -EOPNOTSUPP there each time? >> [...] >>> @@ -2080,6 +2130,9 @@ int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) >>> unsigned long orig_jiffies; >>> int ret, try; >>> >>> + if (adap->quirks && i2c_check_for_quirks(adap, msgs, num)) >> So, you only check for non-zero result of this function? Perhaps it makes >> sense to return true/false instead? > Could be done, but what would be the advantage? A lot of functions > return errno or 0. It would have been OK if you were actually caring about the result, e.g. returning it from __i2c_transfer(). Since you don't, IMO it would make more sense to return true from i2c_check_for_quirks() (making it *bool*) iff it did find/apply a quirk. WBR, Sergei