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[91.79.175.49]) by smtp.googlemail.com with ESMTPSA id w6sm3582050pga.72.2019.02.08.10.06.57 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 08 Feb 2019 10:07:04 -0800 (PST) Subject: Re: [PATCH V17 3/6] i2c: tegra: fix maximum transfer size To: Sowjanya Komatineni , thierry.reding@gmail.com, jonathanh@nvidia.com, mkarthik@nvidia.com, smohammed@nvidia.com, talho@nvidia.com Cc: wsa@the-dreams.de, peda@axentia.se, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org, stable@vger.kernel.org References: <1549648195-3989-1-git-send-email-skomatineni@nvidia.com> <1549648195-3989-3-git-send-email-skomatineni@nvidia.com> From: Dmitry Osipenko Message-ID: <0c30dfe0-1174-0056-5ef6-432b75de2353@gmail.com> Date: Fri, 8 Feb 2019 21:06:54 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.0 MIME-Version: 1.0 In-Reply-To: <1549648195-3989-3-git-send-email-skomatineni@nvidia.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 08.02.2019 20:49, Sowjanya Komatineni пишет: > Tegra194 supports maximum 64K bytes transfer per packet. > Tegra186 and prior supports maximum 4K bytes transfer per packet. > > This includes 12 bytes of packet header and this limit is > applicable irrespective of PIO or DMA mode transfers. > > This patch fixes max write length to account for packet header size > for transfers. > > Cc: stable@vger.kernel.org > > Signed-off-by: Sowjanya Komatineni > --- > [V16/V17] : I2C core max message size is 65536. So, max_read_len of 65535 is NOP. > Removed it leaving max_write_len > [V15] : This is new patch in this series. > > > drivers/i2c/busses/i2c-tegra.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c > index 3758c7a2c781..e4bf85e8dc14 100644 > --- a/drivers/i2c/busses/i2c-tegra.c > +++ b/drivers/i2c/busses/i2c-tegra.c > @@ -125,6 +125,9 @@ > #define I2C_MST_FIFO_STATUS_TX_MASK 0xff0000 > #define I2C_MST_FIFO_STATUS_TX_SHIFT 16 > > +/* Packet header size in bytes */ > +#define I2C_PACKET_HEADER_SIZE 12 > + > /* > * msg_end_type: The bus control which need to be send at end of transfer. > * @MSG_END_STOP: Send stop pulse at end of transfer. > @@ -899,12 +902,13 @@ static const struct i2c_algorithm tegra_i2c_algo = { > /* payload size is only 12 bit */ > static const struct i2c_adapter_quirks tegra_i2c_quirks = { > .flags = I2C_AQ_NO_ZERO_LEN, > - .max_read_len = 4096, > - .max_write_len = 4096, > + .max_read_len = SZ_4K, > + .max_write_len = SZ_4K - I2C_PACKET_HEADER_SIZE, > }; > > static const struct i2c_adapter_quirks tegra194_i2c_quirks = { > .flags = I2C_AQ_NO_ZERO_LEN, > + .max_write_len = 65535 - I2C_PACKET_HEADER_SIZE, Ideally it should be SZ_64K - I2C_PACKET_HEADER_SIZE to not miss the one byte, otherwise good to me: Reviewed-by: Dmitry Osipenko