Messages in this thread | | | Date | Thu, 9 Mar 2023 15:52:59 +0200 | From | Andy Shevchenko <> | Subject | Re: [PATCH v4 2/5] gpio: Add support for Intel LJCA USB GPIO driver |
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On Thu, Mar 09, 2023 at 02:40:10PM +0100, Oliver Neukum wrote: > On 09.03.23 08:10, Ye Xiang wrote: > > > +#define LJCA_GPIO_BUF_SIZE 60 > > +struct ljca_gpio_dev { > > + struct platform_device *pdev; > > + struct gpio_chip gc; > > + struct ljca_gpio_info *gpio_info; > > + DECLARE_BITMAP(unmasked_irqs, LJCA_MAX_GPIO_NUM); > > + DECLARE_BITMAP(enabled_irqs, LJCA_MAX_GPIO_NUM); > > + DECLARE_BITMAP(reenable_irqs, LJCA_MAX_GPIO_NUM); > > + u8 *connect_mode; > > + /* mutex to protect irq bus */ > > + struct mutex irq_lock; > > + struct work_struct work; > > + /* lock to protect package transfer to Hardware */ > > + struct mutex trans_lock; > > + > > + u8 obuf[LJCA_GPIO_BUF_SIZE]; > > + u8 ibuf[LJCA_GPIO_BUF_SIZE]; > > And here we have a violation of DMA coherency rules. > Basically you cannot embed buffers into other data structures > if they can be subject to DMA.
Huh?!
The problem here is alignment. But other than that I can't see the issue with embedding into structures the instances of which will be allocated on the heap.
-- With Best Regards, Andy Shevchenko
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