Messages in this thread | | | Date | Wed, 3 Nov 2021 17:47:37 +0100 | From | Matthias Brugger <> | Subject | Re: [PATCH 3/5] drivers/auxdisplay: senshat: Raspberry Pi Sense HAT display driver |
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On 29/10/2021 23:55, Charles Mirabile wrote: > This patch implements control of the 8x8 RGB LED matrix display. > > Signed-off-by: Charles Mirabile <cmirabil@redhat.com> > Signed-off-by: Mwesigwa Guma <mguma@redhat.com> > Signed-off-by: Joel Savitz <jsavitz@redhat.com> > --- > drivers/auxdisplay/Kconfig | 7 + > drivers/auxdisplay/Makefile | 1 + > drivers/auxdisplay/sensehat-display.c | 258 ++++++++++++++++++++++++++ > 3 files changed, 266 insertions(+) > create mode 100644 drivers/auxdisplay/sensehat-display.c > [....] > diff --git a/drivers/auxdisplay/sensehat-display.c b/drivers/auxdisplay/sensehat-display.c > new file mode 100644 > index 000000000000..5980ad23fd4f > --- /dev/null > +++ b/drivers/auxdisplay/sensehat-display.c [...] > + > +static ssize_t > +sensehat_display_write(struct file *filp, const char __user *buf, size_t count, loff_t *f_pos) > +{ > + struct sensehat *sensehat = container_of(filp->private_data, struct sensehat, display.mdev); > + struct sensehat_display *sensehat_display = &sensehat->display; > + u8 temp[VMEM_SIZE]; > + > + if (*f_pos >= VMEM_SIZE) > + return -EFBIG; > + if (*f_pos + count > VMEM_SIZE) > + count = VMEM_SIZE - *f_pos; > + if (copy_from_user(temp, buf, count)) > + return -EFAULT; > + if (mutex_lock_interruptible(&sensehat_display->rw_mtx)) > + return -ERESTARTSYS; > + memcpy(sensehat_display->vmem + *f_pos, temp, count);
So we copy from buf into temp, from temp into vmem and then we 'transform' vmem into the representation of pixel_data.
As you are implementing the user-space interface, couldn't we just change the pixel representation there and get rid of the transformation?
> + sensehat_update_display(sensehat); > + *f_pos += count; > + mutex_unlock(&sensehat_display->rw_mtx); > + return count; > +} > + > +static long sensehat_display_ioctl(struct file *filp, unsigned int cmd, > + unsigned long arg) > +{ > + struct sensehat *sensehat = container_of(filp->private_data, struct sensehat, display.mdev); > + struct sensehat_display *sensehat_display = &sensehat->display; > + void __user *user_ptr = (void __user *)arg; > + u8 temp[GAMMA_SIZE]; > + int ret; > + > + if (mutex_lock_interruptible(&sensehat_display->rw_mtx)) > + return -ERESTARTSYS; > + switch (cmd) { > + case SENSEDISP_IOGET_GAMMA: > + if (copy_to_user(user_ptr, sensehat_display->gamma, GAMMA_SIZE)) { > + ret = -EFAULT; > + goto out_unlock; > + } > + ret = 0; > + goto out_unlock; > + case SENSEDISP_IOSET_GAMMA: > + if (copy_from_user(temp, user_ptr, GAMMA_SIZE)) { > + ret = -EFAULT; > + goto out_unlock; > + } > + ret = 0; > + goto out_update;
That's just a 'break;' correct?
Regards, Matthias
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