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Tue, 03 Nov 2020 19:35:51 -0800 (PST) Subject: Re: [PATCH v3 5/6] i2c: iproc: handle master read request To: Dhananjay Phadke , rayagonda.kokatanur@broadcom.com References: <20201102035433.6774-6-rayagonda.kokatanur@broadcom.com> <20201102035433.6774-6-rayagonda.kokatanur@broadcom.com> From: Florian Fainelli Message-ID: <861d734f-c776-f70b-e414-a4b32c0f991e@gmail.com> Date: Tue, 3 Nov 2020 19:35:49 -0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: <20201102035433.6774-6-rayagonda.kokatanur@broadcom.com> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201103_223554_803700_E7513299 X-CRM114-Status: GOOD ( 18.20 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: lori.hikichi@broadcom.com, f.fainelli@gmail.com, sbranden@broadcom.com, rjui@broadcom.com, brendanhiggins@google.com, linux-kernel@vger.kernel.org, wsa@kernel.org, bcm-kernel-feedback-list@broadcom.com, linux-i2c@vger.kernel.org, andriy.shevchenko@linux.intel.com, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 11/2/2020 10:19 PM, Dhananjay Phadke wrote: > On Mon, 2 Nov 2020 09:24:32 +0530, Rayagonda Kokatanur wrote: > >> Handle single or multi byte master read request with or without >> repeated start. >> >> Fixes: c245d94ed106 ("i2c: iproc: Add multi byte read-write support for slave mode") >> Signed-off-by: Rayagonda Kokatanur >> --- >> drivers/i2c/busses/i2c-bcm-iproc.c | 215 +++++++++++++++++++++++------ >> 1 file changed, 170 insertions(+), 45 deletions(-) >> >> diff --git a/drivers/i2c/busses/i2c-bcm-iproc.c b/drivers/i2c/busses/i2c-bcm-iproc.c >> index 7a235f9f5884..22e04055b447 100644 >> --- a/drivers/i2c/busses/i2c-bcm-iproc.c >> +++ b/drivers/i2c/busses/i2c-bcm-iproc.c >> @@ -160,6 +160,11 @@ >> >> #define IE_S_ALL_INTERRUPT_SHIFT 21 >> #define IE_S_ALL_INTERRUPT_MASK 0x3f >> +/* >> + * It takes ~18us to reading 10bytes of data, hence to keep tasklet >> + * running for less time, max slave read per tasklet is set to 10 bytes. >> + */ >> +#define MAX_SLAVE_RX_PER_INT 10 >> > > In patch [3/6], you've enabled IS_S_RX_THLD_SHIFT in slave ISR bitmask, > however it's not actually used in processing rx events. > > Instead of hardcoding this threshold here, it's better to add a > device-tree knob for rx threshold, program it in controller and handle > that RX_THLD interrupt. This will give more flexibility to drain the rx > fifo earlier than - > (1) waiting for FIFO_FULL interrupt for transactions > 64B. > (2) waiting for start of read transaction in case of master write-read. The Device Tree is really intended to describe the hardware FIFO size, not watermarks, as those tend to be more of a policy/work load decision. Maybe this is something that can be added as a module parameter, or configurable via ioctl() at some point. -- Florian _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel