linux-kernel - Re: [PATCH v1 5/5] tinydrm: add winstar wg160160 driver

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Message-ID: <20180806091548.yccqipmfyymwnrvy@mwanda>
Date:   Mon, 6 Aug 2018 12:15:48 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     kbuild@...org, Sam Ravnborg <sam@...nborg.org>
Cc:     kbuild-all@...org, Noralf T <noralf@...nnes.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        Sam Ravnborg <sam@...nborg.org>
Subject: Re: [PATCH v1 5/5] tinydrm: add winstar wg160160 driver

Hi Sam,

I love your patch! Perhaps something to improve:

url:    https://github.com/0day-ci/linux/commits/Sam-Ravnborg/dt-bindings-add-parallel-data-bus-pardata/20180803-090135

smatch warnings:
drivers/gpu/drm/tinydrm/wg160160.c:145 write_buf() warn: right shifting more than type allows 8 vs 8
include/drm/tinydrm/pardata-dbi.h:165 pardata_write_buf() error: we previously assumed 'pdd' could be null (see line 162)

# https://github.com/0day-ci/linux/commit/9fcebca9e208029e06eea5e4858c1055132f06b6
git remote add linux-review https://github.com/0day-ci/linux
git remote update linux-review
git checkout 9fcebca9e208029e06eea5e4858c1055132f06b6
vim +145 drivers/gpu/drm/tinydrm/wg160160.c

9fcebca9 Sam Ravnborg 2018-08-02  124  
9fcebca9 Sam Ravnborg 2018-08-02  125  /**
9fcebca9 Sam Ravnborg 2018-08-02  126   * write_buf - write buffer on parallel bus to controller
9fcebca9 Sam Ravnborg 2018-08-02  127   *
9fcebca9 Sam Ravnborg 2018-08-02  128   * @pdd: pardata data
9fcebca9 Sam Ravnborg 2018-08-02  129   * @offset: offset into display RAM
9fcebca9 Sam Ravnborg 2018-08-02  130   * @data: pointer to data to write
9fcebca9 Sam Ravnborg 2018-08-02  131   * @len: number of bytes to write
9fcebca9 Sam Ravnborg 2018-08-02  132   *
9fcebca9 Sam Ravnborg 2018-08-02  133   * Returns:
9fcebca9 Sam Ravnborg 2018-08-02  134   * Zero on success, negative error code on failure
9fcebca9 Sam Ravnborg 2018-08-02  135   */
9fcebca9 Sam Ravnborg 2018-08-02  136  int write_buf(struct pardata_data *pdd, u8 offset, u8 *data, size_t len)
9fcebca9 Sam Ravnborg 2018-08-02  137  {
9fcebca9 Sam Ravnborg 2018-08-02  138  	int ins[PIN_NUM];
9fcebca9 Sam Ravnborg 2018-08-02  139  	int val[PIN_NUM];
9fcebca9 Sam Ravnborg 2018-08-02  140  	int bit;
9fcebca9 Sam Ravnborg 2018-08-02  141  	int i;
9fcebca9 Sam Ravnborg 2018-08-02  142  
9fcebca9 Sam Ravnborg 2018-08-02  143  	/* Setup address */
9fcebca9 Sam Ravnborg 2018-08-02  144  	write_reg(pdd, WG160160_ADDRSL_REG, offset & 0xff);
9fcebca9 Sam Ravnborg 2018-08-02 @145  	write_reg(pdd, WG160160_ADDRSL_REG, (offset >> 8) & 0xff);
                                                                            ^^^^^^^^^^^^^^^^^^^^
Probably this is fine.  I don't know.  If so then feel free to ignore
the warning.

9fcebca9 Sam Ravnborg 2018-08-02  146  
9fcebca9 Sam Ravnborg 2018-08-02  147  	/* prepare to write data */
9fcebca9 Sam Ravnborg 2018-08-02  148  	for (i = 0; i < PIN_NUM; i++)
9fcebca9 Sam Ravnborg 2018-08-02  149  		ins[PIN_DB0 + i] = !!(WG160160_WRITE_REG & BIT(i));
9fcebca9 Sam Ravnborg 2018-08-02  150  
9fcebca9 Sam Ravnborg 2018-08-02  151  	gpiod_set_value_cansleep(pdd->bus->pin_rs, 1);
9fcebca9 Sam Ravnborg 2018-08-02  152  	gpiod_set_array_value_cansleep(PIN_NUM, pdd->bus->data_pins->desc, ins);
9fcebca9 Sam Ravnborg 2018-08-02  153  	wait_busy(pdd);
9fcebca9 Sam Ravnborg 2018-08-02  154  	pardata_strobe_write(pdd);
9fcebca9 Sam Ravnborg 2018-08-02  155  
9fcebca9 Sam Ravnborg 2018-08-02  156  	/* Write data byte - by byte */
9fcebca9 Sam Ravnborg 2018-08-02  157  	gpiod_set_value_cansleep(pdd->bus->pin_rs, 0);
9fcebca9 Sam Ravnborg 2018-08-02  158  
9fcebca9 Sam Ravnborg 2018-08-02  159  	for (i = offset; i < (offset + len); i++) {
9fcebca9 Sam Ravnborg 2018-08-02  160  		for (bit = 0; bit < PIN_NUM; bit++)
9fcebca9 Sam Ravnborg 2018-08-02  161  			val[PIN_DB0 + bit] = !!(data[i] & BIT(bit));
9fcebca9 Sam Ravnborg 2018-08-02  162  
9fcebca9 Sam Ravnborg 2018-08-02  163  		gpiod_set_array_value_cansleep(PIN_NUM,
9fcebca9 Sam Ravnborg 2018-08-02  164  					       pdd->bus->data_pins->desc,
9fcebca9 Sam Ravnborg 2018-08-02  165  					       val);
9fcebca9 Sam Ravnborg 2018-08-02  166  		wait_busy(pdd);
9fcebca9 Sam Ravnborg 2018-08-02  167  		pardata_strobe_write(pdd);
9fcebca9 Sam Ravnborg 2018-08-02  168  	}
9fcebca9 Sam Ravnborg 2018-08-02  169  
9fcebca9 Sam Ravnborg 2018-08-02  170  	return 0;
9fcebca9 Sam Ravnborg 2018-08-02  171  }
9fcebca9 Sam Ravnborg 2018-08-02  172  

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