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Message-ID: <511F4C6B.4030805@asianux.com>
Date: Sat, 16 Feb 2013 17:07:55 +0800
From: Chen Gang <gang.chen@...anux.com>
To: Peter Ujfalusi <peter.ujfalusi@...com>, sameo@...ux.intel.com
CC: Tony Lindgren <tony@...mide.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: [Suggestion] drivers/mfd/twl*: about power_count in twl6040_remove
if necessary to treat 'power_count' as a counter
when power_count is more than 1, we do not really power off it.
this may cause issue:
after finish calling twl6040_remove, another modules still use it.
suggest to give additional check, or synchronisation for other modules.
else (not necessary to treat it as a counter)
better to use it as a boolean value.
it seems 'power_count' may still have chance to be more than 1:
if it is true, we still may can not power off it in twl6040_remove.
another question:
may 'power_count' be a large number (which may cause value overflow) ?
thanks.
gchen.
------------------------------------------------------------------------------
relative calls:
drivers/mfd/twl6040.c:212: twl6040_power(twl6040, 0);
drivers/mfd/twl6040.c:215: twl6040_power(twl6040, 1);
drivers/mfd/twl6040.c:707: twl6040_power(twl6040, 0);
drivers/input/misc/twl6040-vibra.c:100: twl6040_power(info->twl6040, 1);
drivers/input/misc/twl6040-vibra.c:128: twl6040_power(info->twl6040, 0);
sound/soc/codecs/twl6040.c:911: ret = twl6040_power(twl6040, 1);
sound/soc/codecs/twl6040.c:926: twl6040_power(twl6040, 0);
drivers/clk/clk-twl6040.c:51: ret = twl6040_power(twl6040_clk->twl6040, 1);
drivers/clk/clk-twl6040.c:64: ret = twl6040_power(twl6040_clk->twl6040, 0);
drivers/mfd/twl6040.c:
244 int twl6040_power(struct twl6040 *twl6040, int on)
245 {
246 int ret = 0;
247
248 mutex_lock(&twl6040->mutex);
249
250 if (on) {
251 /* already powered-up */
252 if (twl6040->power_count++)
253 goto out;
254
255 if (gpio_is_valid(twl6040->audpwron)) {
256 /* use automatic power-up sequence */
257 ret = twl6040_power_up_automatic(twl6040);
258 if (ret) {
259 twl6040->power_count = 0;
260 goto out;
261 }
262 } else {
263 /* use manual power-up sequence */
264 ret = twl6040_power_up_manual(twl6040);
265 if (ret) {
266 twl6040->power_count = 0;
267 goto out;
268 }
269 }
270 /* Default PLL configuration after power up */
271 twl6040->pll = TWL6040_SYSCLK_SEL_LPPLL;
272 twl6040->sysclk = 19200000;
273 twl6040->mclk = 32768;
274 } else {
275 /* already powered-down */
276 if (!twl6040->power_count) {
277 dev_err(twl6040->dev,
278 "device is already powered-off\n");
279 ret = -EPERM;
280 goto out;
281 }
282
283 if (--twl6040->power_count)
284 goto out;
285
286 if (gpio_is_valid(twl6040->audpwron)) {
287 /* use AUDPWRON line */
288 gpio_set_value(twl6040->audpwron, 0);
289
290 /* power-down sequence latency */
291 usleep_range(500, 700);
292 } else {
293 /* use manual power-down sequence */
294 twl6040_power_down_manual(twl6040);
295 }
296 twl6040->sysclk = 0;
297 twl6040->mclk = 0;
298 }
299
300 out:
301 mutex_unlock(&twl6040->mutex);
302 return ret;
303 }
304 EXPORT_SYMBOL(twl6040_power);
...
702 static int twl6040_remove(struct i2c_client *client)
703 {
704 struct twl6040 *twl6040 = i2c_get_clientdata(client);
705
706 if (twl6040->power_count)
707 twl6040_power(twl6040, 0);
708
709 if (gpio_is_valid(twl6040->audpwron))
710 gpio_free(twl6040->audpwron);
711
712 free_irq(twl6040->irq_ready, twl6040);
713 free_irq(twl6040->irq_th, twl6040);
714 regmap_del_irq_chip(twl6040->irq, twl6040->irq_data);
715
716 mfd_remove_devices(&client->dev);
717 i2c_set_clientdata(client, NULL);
718
719 regulator_bulk_disable(TWL6040_NUM_SUPPLIES, twl6040->supplies);
720 regulator_bulk_free(TWL6040_NUM_SUPPLIES, twl6040->supplies);
721
722 return 0;
723 }
-----------------------------------------------------------------------------------
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